Family Matters - Cognitive Classes and Social Behavior - The Bell Curve: Intelligence and Class Structure in American Life - Richard J. Herrnstein, Charles Murray

The Bell Curve: Intelligence and Class Structure in American Life - Richard J. Herrnstein, Charles Murray (1996)

Part II. Cognitive Classes and Social Behavior

Chapter 8. Family Matters

Rumors of the death of the traditional family have much truth in them for some parts of white American society—those with low cognitive ability and little education—and much less truth for the college educated and very bright Americans of all educational levels. In this instance, cognitive ability and education appear to play mutually reinforcing but also independent roles.

For marriage, the general rule is that the more intelligent get married at higher rates than the less intelligent. This relationship, which applies across the range of intelligence, is obscured among people with high levels of education because college and graduate school are powerful delayers of marriage.

Divorce has long been more prevalent in the lower socioeconomic and educational brackets, but this turns out to be explained better by cognitive level than by social status. Once the marriage-breaking impact of low intelligence is taken into account, people of higher socioeconomic status are more likely to get divorced than people of lower status.

Illegitimacy, one of the central social problems of the times, is strongly related to intelligence. White women in the bottom 5 percent of the cognitive ability distribution are six times as likely to have an illegitimate first child as those in the top 5 percent. One out of five of the legitimate first babies of women in the bottom 5 percent was conceived prior to marriage, compared to fewer than one out of twenty of the legitimate babies to women in the top 5 percent. Even among young women who have grown up in broken homes and among young women who are poor—both of which foster illegitimacy—low cognitive ability further raises the odds of giving birth illegitimately. Low cognitive ability is a much stronger predisposing factor for illegitimacy than low socioeconomic background.

At lower educational levels, a woman’s intelligence best predicts whether she will bear an illegitimate child. Toward the higher reaches of education, almost no white women are having illegitimate children, whatever their family background or intelligence.

The conventional understanding of troubles in the American family has several story lines. The happily married couple where the husband works and the wife stays home with the children is said to be as outmoded as the bustle. Large proportions of young people are staying single. Half the marriages end in divorce. Out-of-wedlock births are soaring.

These features of modern families are usually discussed in the media (and often in academic presentations) as if they were spread more or less evenly across society1 In this chapter, we introduce greater discrimination into that description. Unquestionably, the late twentieth century has seen profound changes in the structure of the family. But it is easy to misperceive what is going on. The differences across socioeconomic classes are large, and they reflect important differences by cognitive class as well.

MARRIAGE

Marriage is a fundamental building block of social life and society itself and thus is a good place to start, because this is one area where much has changed and little has changed, depending on the vantage point one takes.

From a demographic perspective, the changes are huge, as shown in the next figure. The marriage rate since the 1920s has been volatile, but the valleys and peaks in the figure have explanations that do not necessarily involve the underlying propensity to marry. The Great Depression probably had a lot to do with the valley in the early 1930s, and World War II not only had a lot to do with the spike in the late 1940s but may well have had reverberations on the marriage rate that lasted into the 1950s. It could even be argued that once these disruptive events are taken into account, the underlying propensity to marry did not change from 1930 to the early 1970s. The one prolonged decline for which there is no obvious explanation excepta change in the propensity to marry began in 1973, when marriage rates per 1,000 women began dropping and have been dropping ever since, in good years and bad. In 1987, the nation passed a landmark: Marriage rates hit an all-time low, dropping below the previous mark set in the depths of the depression. A new record was promptly set again in 1988.

This change, apparently reflecting some bedrock shifts in attitudes toward marriage in postindustrial societies, may have profound significance. And yet marriage is still alive and well in the sense that it remains a hugely popular institution. Over 90 percent of Americans of both sexes have married by the time they reach their 40s.2

In the early 1970s, the marriage rate began a prolonged decline for no immediately apparent reason

Imag

Sources: U.S. Bureau of the Census, 1975, Table B214-215; SAUS, 1992, Table 127, and comparable tables in various editions.

Marriage and IQ

What does cognitive ability have to do with marriage, and is there any reason to think that it could be interacting with society’s declining propensity to marry?

We know from work by Robert Retherford that in premodern societies the wealthy and successful married at younger ages than the poor and underprivileged.3 Retherford further notes that intelligence and social status are correlated wherever they have been examined; hence, we can assume that intelligence—via social status—facilitated’marriage in premodern societies.

With the advent of modernity, however, this relationship flips over. Throughout the West since the nineteenth century, people in the more privileged sector of society have married later and at lower rates than the less privileged. We examine the demographic implications of this phenomenon in Chapter 15. For now, the implication is that in late-twentieth-century America, we should expect to find lower marriage rates among the highly intelligent in the NLSY.

Everyday experience bears out this finding for people who live in academic communities or professional circles, where they see many smart men and women in their 30s and 40s who are still single and look as if they might stay that way forever. The intelligent professional woman is the most visible of this new tribe, rising in her career, too busy for, or not interested in, marriage and children. Among men, other images have recently become part of the culture: the intelligent, successful, and unmarried heterosexual male who cannot make a commitment and the intelligent, successful, and unmarried homosexual male who no longer needs to go through the motions of a marriage.

At the other end of the scale, there are similar reasons in research and common sense to suggest that marriage rates will tend to be low among people at the very bottom of the IQ distribution.4 For a number of reasons, having to do with everything from initiative to romance to economics, people with very low IQs are likely to be at a disadvantage in competing for marriage partners.

Our first look at the NLSY data conforms to these expectations, though not dramatically. The next table shows the situation for the NLSY sample among whites who had reached the age of 30. There were surprises in these results for us, and perhaps for some of our readers. We would not have guessed that the average age of marriage for people in the top 5 percent of the intelligence distribution was only 25, for example.5 A main point of the table is to introduce the theme threaded throughout the chapter: Our, your, and the media’s impressions of the state of the American family are not necessarily accurate.

The Role of Socioeconomic Background

Note in the table below that marriage percentages are highest for people in the middle of the intelligence distribution and taper off on both ends. The same is true, though less dramatically, if the table is constructed by socioeconomic class: The percentage of whites who had married before the age of 30 declines at both extremes. Furthermore, we have good reasons for thinking that this pattern is not a sampling fluke but reflects underlying dynamics of marriage. This pattern makes interpreting regression results tricky, because the regression techniques we are using compute the lines in the graphs based on the assumption that the lines are not trying to make U-turns. For the record: When we run the standard initial analysis incorporating IQ, age, and socioeconomic status as predictors of marriage, IQ has no significant independent role; there is a slight, statistically insignificant downward probability of marriage as IQ goes up. Socioeconomic background has a much larger suppressive role on marriage: The richer and better educated your parents, the less likely you are to marry, according to these results, which, again, must be interpreted cautiously.

Which Whites Get Married When?

Percentage Who Had Ever Married Before Age 30

Cognitive Class

Average Age at First Marriage

67

I Very bright

25.4

72

II Bright

24.3

81

III Normal

22.9

81

IV Dull

21.5

72

V Very Dull

21.3

78

Overall averages

22.1

The Role of Education

The real culprit in explaining marriage rates in a young population is education. In the rest of the chapters of Part II, we point out many instances in which taking education into account does not much affect IQ’s independent role. Not so with marriage. When we take education into account, the apparent relationship reverses: The probability of marrying goes up, not down, for people with high IQs—a result found in other databases as well.6 Our standard analysis with the two educational samples, high school graduates (no more and no less) and college graduates (no more and no less) elucidates this finding.

The next figure shows that neither IQ nor socioeconomic background was important in determining marriage for the college sample. In sharp contrast, IQ made a significant difference in the high school sample. A high school graduate from an average socioeconomic background who was at the bottom of the IQ distribution (2 standard deviations below the mean) had a 60 percent chance of having married. A high school graduate at the top of the IQ distribution had an 89 percent chance of having married. Meanwhile, the independent role of socioeconomic status in the high school sample was either slightly negative or nil (the downward slope is not statistically significant).

High IQ raises the probability of marriage for the white high school sample, while high socioeconomic background lowers it

Imag

Note: For computing the plot, age, and either SES (for the black curves) or IQ (for the gray curves) were set at their mean values.

DIVORCE

People marry, but do they stay married? Here is where the change has been not only dramatic but, some would say, cataclysmic, as shown below. In 1920, only death parted husbands and wives in about 82 percent of marriages and, in any given year (the datum shown in the next figure below), only about 8 out of 1,000 married females experienced a divorce. As late as 1964, despite the sweeping changes in technology, wealth, and social life that had occurred in the intervening forty-four years, the number was very little changed: 10 of every 1,000. The peak divorce rates just following World War II had fully subsided, and the divorce rate still lay upon a trendline established between 1920 and 1940.

The divorce revolution

Imag

Sources: U.S. Bureau of the Census, 1975, Table B214-215; SAUS, 1992, Table 127, and comparable table in various editions.

Then came the revolution. The steep upward sweep of the divorce rate from the mid-1960s through the end of the 1970s represents one of the most rapid, compressed changes in a basic social behavior that the twentieth century has witnessed. When the divorce rate hit its peak at the end of the 1970s, a marriage had more than a fifty-fifty chance of ending in divorce.7 Despite a downward trend since 1980, divorce remains at twice the annual rate of the mid-1960s.

Divorce and IQ

We do not attempt to explain this profound change in our lives, which no doubt has roots in changing mores, changing laws, changing roles of women, changing labor markets, and who knows what else. Instead, we address the narrow question: How does divorce currently correlate with intelligence?

There are plausible reasons for expecting that cognitive ability will have an impact on divorce. For example, one may hypothesize that bright people less often marry on a whim, hence they have fewer disastrous short marriages. Bright people are perhaps less likely to act on impulse when the marriage has problems, hence are less likely to divorce precipitously during the first years of marriage. More generally, it may be argued that brighter people are better able to work out differences that might otherwise eventually destroy a marriage. We are, of course, referring to statistical tendencies for which individual exceptions abound.

Within the confines of the NLSY experience, these expectations are borne out to some degree, as shown in the table. The results are based on the first five years of marriage. Those in Class I were ten times as likely to stay married for at least five years as to get divorced; for those in Classes III, IV, and V—the bottom three-quarters of the population—the ratio of marital survival to divorce for at least five years was only 3.5 to 1.8 Virtually all of the effect of IQ seems to have been concentrated at the top of the distribution. The divorce rates across the bottom three-quarters of the cognitive ability distribution were essentially identical.

Which Whites Get Divorced When?

Cognitive Class

Percentage Divorced in First Five Years of Marriage

I Very bright

9

II Bright

15

III Normal

23

IV Dull

22

V Very dull

21

Overall averages

20

The Role of Socioeconomic Background

Do these findings hold up when we begin to add in other considerations? The figure below shows the results for the white sample who had been married at least five years.9 The consistent finding, represented fairly by the figure, was that higher IQ was still associated with a lower probability of divorce after extracting the effects of other variables, and parental SES had a significant positiverelationship to divorce—that is, IQ being equal, children of higher-status families were more likely to get divorced than children of lower-status families.10

IQ and socioeconomic background have opposite effects on the likelihood of an early divorce among young whites

Imag

Note: In addition to IQ, age, and parental SES, the independent variables included date of first marriage. For computing the plot, age, date of first marriage, and either SES (for the black curve) or IQ (for the gray curve) were set at their mean values.

The Role of Education

It is clear to all researchers who examine the data that higher education is associated with lower levels of divorce. This was certainly true of the NLSY, where the college sample (persons with a bachelor’s degree, no more and no less) had a divorce rate in the first five years of marriage that was less than half that of the high school sample: 7 percent compared to 19 percent. But this raw outcome is deceptive.11 Holding some critical other things equal—IQ, socioeconomic status, age, and date of marriage—the divorce rate for the high school graduates in the first five years of marriage was lowerthan for college graduates.

For whom did IQ make more difference: the high school sample or the college sample? The answer is the college sample, by far. For them, the probability of divorce in the first five years plunged from 28 percent for someone with an IQ of 100 to 9 percent for someone with an IQ of 130. The much more minor effect of IQ among high school graduates was not statistically significant.12

Do Broken Families Beget Broken Families?

One other cause of divorce is mentioned so commonly that it requires exploration: a broken home in the preceding generation. The children of divorced parents have an elevated risk themselves of getting divorced.13 It is not hard to think of reasons why: They have not witnessed how a successful marriage works, they are more likely to see divorce as an acceptable alternative, the turbulence of a failing marriage leaves psychological scars, and so forth.14

None of these reasons has an obvious connection with cognitive ability. They could be valid without necessarily affecting the independent prophylactic role that being smart plays in preventing (or perhaps simply delaying) divorce. And so indeed it worked out in the NLSY. Given a young person of average IQ and socioeconomic background, the probability of divorce within the first five years of marriage was lowest for those who at age 14 had been living with both parents (20 percent), a bit higher for those who had been living with a remarried parent (22 percent), and higher still for those living with an un-remarried or never-married mother (25 percent)15 These are not large effects, however, and are not significant in a statistical sense. We can say only that the results supported the general proposition that, when it comes to raising children who will themselves stay married, two adults as parents are generally better than one and that two biological parents in the household are better than one or none. But it is worth noting that the introduction of these variables did nothing to change the importance of the rest of the variables. Higher cognitive ability conferred just about as much protection from, and higher status just as much risk for, divorce as in the preceding analyses.

The NLSY gives us a window on the early years of marriage, though not necessarily about marriage as a whole. Based on national divorce rates, we know that most of the divorces that the members of the NLSY will experience have yet to occur. We will have to wait and see what happens to the NLSY sample in later years.

One final point about the divorce results is worth noting, however. These findings may help explain the common observation that divorce is less likely when the husband has high education, income, or socioeconomic status or that marriages are more likely to fall apart if they start when the couple is afflicted with unemployment.16 If we had showed a breakdown of divorce rates in the NLSY by social and economic measures alone, we too would have shown such effects. But each of those variables is correlated with cognitive ability, and the studies that examine them almost never include an independent measure of intelligence per se. Some portion of what has so often been observed about the risk factors for divorce turns out to be more narrowly the result of low cognitive ability.

ILLEGITIMACY

Childbearing touches on one of the most sensitive topics in the study of intelligence and its social consequences: fertility patterns among the smart and the dumb, and their possible long-term effects on the intellectual capital of a nation’s population. We devote a full chapter to this topic (Chapter 15) in the portion of the book dealing with the national, multiracial perspective. In this chapter, the focus is on family problems, and one of the leading current problems is the failure of two-parent families to form in the first place, as denoted by births to single women—illegitimacy.

We use the older term “illegitimacy” in favor of the phrases currently in favor, “out-of-wedlock births” or “births to single women,” because we think that, in the long run, the word illegitimacy will prove to be the right one. We are instructed in this by the anthropologist Bronis-law Malinowski. In his research early in the century, Malinowski observed a constant running throughout the rich diversity of human cultures and indeed throughout history. He decided that this amounted to “a universal sociological law” and called it the “principle of legitimacy.” No matter what the culture might be, “there runs the rule that the father is indispensable for the full sociological status of the child as well as of the mother, that the group consisting of a woman and her offspring is sociologically incomplete and illegitimate.”17 The rule applied alike to East or West, primitive cultures or advanced ones, cultures where premarital sex was accepted or banned, where children were considered an asset or a burden, where fathers could have one wife or many. Despite our faith that Malinowski was observing something that will once again be considered true about human societies, the contemporary Western democracies, including the United States, seem intent on proving Malinowski wrong, as shown in the next figure.

The illegitimacy revolution

Imag

Sources: Various editions of the Natality volume of Vital Statistics, compiled annually by the Public Health Service.

In the seventy-one years from 1920 to 1990, the proportion of children born to single women in the United States went from less than 3 percent, roughly where it had been throughout American history, to 30 percent.18 It would have been about 6 percent had the trendline established from 1920 to 1952 remained unchanged. The trendline shifted upward during the 1950s, but not dramatically. If we had maintained the trendline established from 1952 to 1963, the United States would have had about 11 percent of births out of wedlock in 1991. Instead, the figure was 30 percent, the result of a steep, sustained increase that gatlered steam in the mid-1960s and continued into the early 1990s. The increase for the most recent available year, 1991, was one of the largest in history. There are no signs as we write that illegitimacy is reaching an asymptote.

Anyone who is trying to understand social trends must also realize that the magic of compound interest has created an even more explosive rise in the population of unmarried mothers and children. In 1960, for example, there were just 73,000 never-married mothers between the ages of 18 and 34. In 1980, there were 1.0 million.19 In 1990, there were approximately 2.9 million.20 Thus the illegitimacy ratio increased by sixfold from 1960 to 1990—bad enough—but the number of never-married mothers increased fortyfold. From just 1980 to 1990, while the illegitimacy ratio was increasing by half, the number of unmarried mothers almost tripled.

Illegitimacy and IQ

If IQ is a factor in illegitimacy, as we will conclude it is, it must be in combination with other things (as common sense would suggest), because IQ itself has not changed nearly enough in recent years to account for the explosive growth in illegitimacy.21 But we will also be exploring the possibility that some of these “other things” that have changed in the last three decades—broken homes and the welfare system being prime suspects—interact with intelligence, making it still more likely than before that a woman of low cognitive ability will have a baby out of wedlock.

Among other reasons that cognitive ability may be related to illegitimacy, we have this causal model in mind: The smarter a woman is, the more likely that she deliberately decides to have a child and calculates the best time to do it. The less intelligent the woman is, the more likely that she does not think ahead from sex to procreation, does not remember to use birth control, does not carefully consider when and under what circumstances she should have a child. How intelligent a woman is may interact with her impulsiveness, and hence her ability to exert self-discipline and restraint on her partner in order to avoid pregnancy. The result is a direct and strong relationship between high intelligence and the likelihood that a child is conceived after marriage, and between low intelligence and the likelihood that the child will be born out of wedlock.

There are, of course, objections to this explanation. Some will bristle at our identification of conception within marriage with the intelligent thing to do. But is it really controversial or even arguable? Under what circumstances can a thoughtful, coolheaded appraisal lead one to conclude that it is better to conceive a child outside marriage? If such circumstances exist, are they not exceptional? Perhaps a woman wants to conceive a child out of marriage, but how likely is it that a disinterested person would consider it to be in the best interest of all concerned, including the child’s?

We begin our exploration with the overall numbers. First, how many white women are engaging in this behavior? As the next table shows, the differences among the cognitive classes are extremely large. Only 2 percent of white women in Class I had given birth to an illegitimate child as of the 1990 interview, compared to 32 percent of the women in Class V.

The Incidence of Illegitimacy Among Young White Women

Cognitive Class

Percentage Who Have Given Birth to an Illegitimate Baby

I Very bright

2

II Bright

4

III Normal

8

IV Dull

17

IV Very dull

32

Overall average

8

Now we switch lenses. Instead of asking how many women have ever had an illegitimate baby, we ask what proportion of first babies born to white women are illegitimate. The next table shows the results. The proportions of illegitimate first births in the top two cognitive classes are nearly the same, rounding to 7 percent—about half the proportion for Class III, a third of the proportion for Class IV, and a sixth of the proportion for Class V. Illegitimacy is again conspicuously concentrated in the lowest cognitive groups.

The Proportion of White First Births That Are Illegitimate

Cognitive Class

Percentage of Illegitimate Births

I Very bright

7

II Bright

7

III Normal

13

IV Dull

23

V Very dull

42

Overall average

14

The relationship between intelligence and illegitimacy is strong not only in these basic respects, but also in more subtle ways, as the numbers based on the women’s first births, shown in the next table, reveal. Not only are children of mothers in the top quartile of intelligence (Classes I and II) more likely to be born within marriage, they are more likely to have been conceived within marriage (no shotgun wedding). The differences among the cognitive classes are large, as if they lived in different worlds. For the women in Class V, only 47 percent of the first children were conceived after a marriage ceremony; for the women in Class I, 89 percent.

Circumstances of the First Birth Among Whites

Born Illegitimate

Born After Marriage

Mother Hasn’t Marrieda

Mother Eventually Marrieda

Cognitive Class

Conceived Before Marriage

Conceived After Marriage

aBy the time of the 1990 interview.

3%

4%

I Very bright

4%

89%

3

4

II Bright

13

80

3

10

III Normal

20

67

7

16

IV Dull

22

55

17

24

V Very Dull

12

47

4

10

Population

19

68

The table makes a strong prima facie case for a relationship between cognitive ability and illegitimacy. The question is whether it survives scrutiny when we introduce other factors into the analysis.22

The Role of Socioeconomic Background

The socioeconomic background of a young woman was traditionally thought to be crucial in determining whether she bore a child out of wedlock. The old-fashioned view of illegitimacy was that it occurred mostly among girls from the lower classes, with occasional and scandalous slip-ups by higher-class “good girls” who “got in trouble.” But during the last few decades, as births outside marriage became more common and as examples proliferated of film stars and career women who were choosing to have babies without husbands, an alternative view spread. The sexual revolution had obviously penetrated to all levels of society, it was argued, and births out of wedlock were occurring at all levels of our sexually liberated society.

There were never any systematic data to support this view, but neither did scholars rush to check it out. A 1980 article in the American Sociological Reviewon education and fertility reported that white women with less than a high school education were twenty times more likely to have a child out of wedlock than white women with at least a college degree, but illegitimacy was only a side issue in the article and the datum never got noticed in the public dialogue.23 The relationship of teenage illegitimacy to social and cognitive factors was first treated in detail in an analysis of the High School and Beyond survey published by the RAND Corporation in 1988.24 The report revealed that more than three-quarters of the teenage girls in this national sample who had babies while they were still of high school age came from families in the bottom half of the socioeconomic stratum. More than half came from the bottom quartile. This finding also held true among just the white teenage girls who had babies out of wedlock, with 70 percent coming from the bottom half of the socioeconomic distribution and only 12 percent from the top quartile.25 The RAND study was also the first to reveal that cognitive ability played an important role, independent of socioeconomic status.26

The data from the NLSY generally confirm those reported in the RAND analysis. On the surface, white illegitimacy is associated with socioeconomic status: About 9 percent of babies of women who come from the upper socioeconomic quartile are illegitimate, compared to about 23 percent of the children of women who come from the bottom socioeconomic quartile. But white women of varying status backgrounds differ in cognitive ability as well. Our standard analysis with IQ, age, and parental SES as independent variables helps to clarify the situation. The dependent variable is whether the first child was born out of wedlock.27

IQ has a large effect on white illegitimate births independent of the mother’s socioeconomic background

Imag

Note: For computing the plot, age and either SES (for the black curve) or IQ (for the gray curve) were set at their mean values.

Higher social status reduces the chances of an illegitimate first baby from about 19 percent for a woman who came from a very low status family to about 8 percent for a woman from a very high status family, given that the woman has average intelligence. Let us compare that 11 percentage point swing with the effect of an equivalent shift in intelligence (given average socioeconomic background ).28 The odds of having an illegitimate first child drop from 34 percent for a very dull woman to about 4 percent for a very smart woman, a swing of 30 percentage points independent of any effect of socioeconomic status.

The Role of Education

Without doubt, the number of well-educated women who are deliberately deciding to have a baby out of wedlock—the name “Murphy Brown” comes to mind—has increased. The Bureau of the Census’s most recent study of fertility of American women revealed that the percentage of never-married women with a bachelor’s degree who had a baby had increased from 3 to 6 percent from 1982 to 1992.29 But during the same decade, the percentage of never-married women with less than a high school education who had a baby increased from 35 to 48 percent.30 The role of education continues to be large.

In the NLSY, the statistics contrast even more starkly. Among white women in the NLSY who had a bachelor’s degree (no more, no less) and who had given birth to a child, 99 percent of the babies were born within marriage. In other words, there is virtually no independent role for IQ to play among women in the college sample. It is true that the women in that 1 percent who gave birth out of wedlock were more likely to have the lower test scores—independent of any effect of their socioeconomic backgrounds—but this is of theoretical interest only.

Meanwhile, for white women in the NLSY who had a high school diploma (no more, no less) and had given birth to a child, 13 percent of the children had been born out of wedlock (compared to 1 percent for the college sample). For them, the independent role of IQ was as large as the one for the entire population (as shown in the preceding figure). A high school graduate with an IQ of 70 had a 34 percent probability that the first baby would be born out of wedlock; a high school graduate with an IQ of 130 had less than a 3 percent chance, after extracting the effects of age and socioeconomic background. The independent effect of socioeconomic status was comparatively minor.

The Role of Broken Homes

We have already noted that family structure at the age of 14 had only modest influence on the chances of getting divorced in the NLSY sample after controlling for IQ and parental SES. Now the question is how the same characteristic affects illegitimacy. Let us consider a white woman of average intelligence and average socioeconomic background. The odds that her first child would be born out of wedlock were:

10 percent if she was living with both biological parents.

18 percent if she was living with a biological parent and a stepparent.

25 percent if she was living with her mother (with or without a live-in boyfriend).

The difference between coming from a traditional family versus anything else was large, with the stepfamily about halfway between the traditional family and the mother-only family.

As we examined the role of family structure with different breakdowns (the permutations of arrangements that can exist are numerous), a few patterns kept recurring. It seemed that girls who were still living with their biological father at age 14 were protected from having their first baby out of wedlock. The girls who had been living with neither biological parent (usually living with adopted parents) were also protected. The worst outcomes seemed conspicuously associated with situations in which the 14-year-old had been living with the biological mother but not the biological father. Here is one such breakdown. The odds that a white woman’s first baby would be born out of wedlock (again assuming average intelligence and socioeconomic background) were:

8 percent if the biological mother, but not the biological father, was absent by age 14.

8 percent if both biological parents were absent at age 14 (mostly adopted children).

10 percent if both biological parents were present at age 14.

23 percent if the biological father was absent by age 14 but not the biological mother.

There is considerable food for thought here, but we refrain from speculation. The main point for our purposes is that family structure is clearly important as a cause of illegitimacy in the next generation.

Did cognitive ability still continue to play an independent role? Yes, for all the different family configurations that we examined. Indeed, the independent effect of IQ was sometimes augmented by taking family structure into account. Consider the case of a young woman at risk, having lived with an unmarried biological mother at age 14. Given average socioeconomic background and an average IQ, the probability that her first baby would be born out of wedlock was 25 percent. If she had an IQ at the 98th centile (an IQ of 130 or above), the probability plunged to 8 percent. If she had an IQ at the 2d centile (an IQ of 70 or below), the probability soared to 55 percent. High socioeconomic status offered weak protection against illegitimacy once IQ had been taken into account.31

The Role of Poverty and Welfare

In the next chapter, we discuss IQ in relation to welfare dependence. Here, we take up a common argument about welfare as a cause of illegitimacy. It is not that low IQ causes women to have illegitimate babies, this argument suggests, but that the combination of poverty and welfare causes women to have illegitimate babies. The logic is that a poor woman who is assured of clothes, shelter, food, and medical care will take fewer precautions to avoid getting pregnant, or, once pregnant, will put less pressure on the baby’s father to marry her, than a woman who is not assured of support. There are two versions of the argument. One sees the welfare system as bribing women to have babies; they get pregnant so they can get a welfare check. The alternative, which we find more plausible, is that the welfare check (and the collateral goods and services that are part of the welfare system) enableswomen to do something that many young women might naturally like to do anyway: bear children.

The controversy about the welfare explanation, in either the “enabling” or “bribe” version, has been intense, with many issues still unresolved.32 Whichever version is employed, the reason for focusing on the role of poverty is obvious: For affluent young women, the welfare system is obviously irrelevant. They are restrained from having babies out of wedlock by moral considerations or by fear of the social penalties (both of which still exist, though weakened, in middle-class circles), by a concern that the child have a father around the house, and because having a baby would interfere with their plans for the future. In the poorest communities, having a baby out of wedlock is no longer subject to social stigma, nor do moral considerations appear to carry much weight any longer; it is not irresponsible to have a child out of wedlock, the argument is more likely to go, because a single young woman can in fact support the child without the help of a husband.33 And that brings the welfare system into the picture. For poor young women, the welfare system is highly relevant, easing the short-term economic penalties that might ordinarily restrain their childbearing.34 The poorer she is, the more attractive the welfare package is and the more likely that she will think herself enabled to have a baby by receiving it.

Given this argument and given that poverty and low IQ are related, let us ask whether the apparent relationship between IQ and illegitimacy is an artifact. Poor women disproportionately have low IQs, and bear a disproportionate number of illegitimate babies. Control for the effects of poverty, says this logic, and the relationship between IQ and illegitimacy will diminish.

Let us see. First, we ask whether the initial condition is true: Is having babies out of wedlock something that is done disproportionately not only by women who come from low socioeconomic backgrounds (a fact which we already have discussed), but women who are literally poor themselves when they reach childbearing age? Even more specifically, are they disproportionately living below the poverty line before the birth?We use the italics to emphasize a distinction that we believe offers an important new perspective on single motherhood and poverty. It is one thing to say that single women with babies are disproportionately poor, as we discussed in Chapter 5. That makes sense, because a single woman with a child is often not a viable economic unit. It is quite another thing to say that women who are already poor become mothers. Now we are arguing that there is something about being in the state of poverty itself (after holding the socioeconomic status in which they were raised constant) that makes having a baby without a husband attractive.

To put the question in operational terms: Among NLSY white mothers who were below the poverty line in the year prior to giving birth, what proportion of the babies were born out of wedlock? The answer is 44 percent. Among NLSY white mothers who were anywhere abovethe poverty line in the year before giving birth, what proportion of the babies were born out of wedlock? The answer is only 6 percent. It is a huge difference and makes a prima facie case for those who argue that poverty itself, presumably via the welfare system, is an important cause of illegitimacy.

But now we turn to the rest of the hypothesis: that controlling for poverty will explain away at least some of the apparent relationship between IQ and illegitimacy. Here is the basic analysis—controlling for IQ, parental SES, and age—restricted to white women who were poor the year before the birth of their babies.35

Compare the graph below with the one before it and two points about white poor women and illegitimacy are vividly clear. First, the independent importance of intelligence is even greater for poor white women than for white women as a whole. A poor white woman of average socioeconomic background and average IQ has more than a 35 percent chance of an illegitimate first birth. For white women in general, average socioeconomic status and IQ resulted in less than a 15 percent chance. Second, among poor women, the role of socioeconomic background in restraining illegitimacy disappears once the role of IQ is taken into account.

IQ is a more powerful predictor of illegitimacy among poor white women than among white women as a whole

Imag

Note: For computing the plot, age and either SES (for the black curve) or IQ (for the gray curve) were set at their mean values.

The results, taken literally, suggest that illegitimacy tends to rise among poor women who came from higher socioeconomic background after IQ is taken into account. However, the sample of white women includes too few women who fit all of the conditions (below the poverty line, from a good socioeconomic background, with an illegitimate baby) to make much of this. The more conservative interpretation is that low socioeconomic background, independent of IQ and current poverty itself, does not increase the chances of giving birth out of wedlock among poor white women—in itself a sufficiently provocative finding for sociologists.36

Our main purpose has been to demonstrate that low intelligence is an important independent cause of illegitimacy, and to do so we have considered the role of poverty. In reality, however, we have also opened up many new avenues of inquiry that we cannot fully pursue without writing an entire book on this subject alone. For example, the results raise many questions to be asked about the “culture of poverty” argument. To the extent that a culture of poverty is at work, transmitting dysfunctional values from one generation to the next, it seems paradoxical that low socioeconomic background does not foster illegitimacy once poverty in the year prior to birth is brought into the picture.

But the main task posed by these results is to fill in the reason for that extremely strong relationship between low IQ and illegitimacy within the population of poor white women. The possibilities bear directly on some of the core issues in the social policy debate. For example, many people have argued that the welfare system cannot really be a cause of illegitimacy, because, in objective terms, the welfare system is a bad deal. It provides only enough to squeak by, it can easily trap young women into long-term dependence, and even poor young women would be much better off by completing their education and getting a job rather than having a baby and going on welfare. The results we have presented can be interpreted as saying that the welfare system may be a bad deal, but it takes foresight and intelligence to understand why. For women without foresight and intelligence, it may seem to be a good deal. Hence poor young women who are bright tend not to have illegitimate babies nearly as often as poor young women who are dull.

Another possibility fits in with those who argue that the best preventative for illegitimacy is better opportunities. It is not the welfare system that is at fault but the lack of other avenues. Poor young women who are bright are getting scholarships, or otherwise having positive incentives offered to them, and they accordingly defer childbearing. Poor young women who are dull do not get such opportunities; they have nothing else to do, and so have a baby. The goal should be to provide them too with other ways of seeing their futures.

Both of these explanations are stated as hypotheses that we hope others will explore. Those explorations will have to incorporate our central finding, however: Cognitive ability in itself is an important factor in illegitimacy, and the dynamics for understanding illegitimacy—and dealing with it through policy—must take that strong link into account.

THE SELECTIVE DETERIORATION OF THE TRADITIONAL FAMILY

Our goal has been to sharpen understanding of the much-lamented breakdown of the American family. The American family has been as battered in the latter decades of the twentieth century as the public rhetoric would have it, but the damage as measured in terms of divorce and illegitimacy has been far more selective than we hear. By way of summary, let us consider the children of the white NLSY mothers in the top quartile of cognitive ability (Classes I and II) versus those in the bottom quartile (Classes IV and V):

The percentage of households with children that consist of a married couple:87 percent in the top quartile of IQ, 70 percent in the bottom quartile.

The percentage of households with children that have experienced divorce:17 percent in the top quartile of IQ, 33 percent in the bottom quartile.

The percentage of children born out of wedlock: 5percent in the top quartile of IQ, 23 percent in the bottom quartile.

The American family may be generally under siege, as people often say. But it is at the bottom of the cognitive ability distribution that its defenses are most visibly crumbling.