The Intelligence Paradox: Why the Intelligent Choice Isn't Always the Smart One - Satoshi Kanazawa 2012

Intelligence and the Value for Children
Why Intelligent People Are the Ultimate Losers in Life

At age 23, near the beginning of the reproductive careers of most British people, NCDS asked its respondents how many children they wanted to have in their lives. More intelligent NCDS respondents wanted significantly fewer children than their less intelligent counterparts. Childhood general intelligence has a significantly negative effect on how many children they want, for both men and women. The more intelligent they are in childhood, the fewer children they want in adulthood.

As you can see in Figure 12.1, women who do not want to have any children at all in their lives have significantly higher childhood IQ than those who want at least one child. Those who want no children have a mean childhood IQ of 105.5 whereas those who want some children have a mean childhood IQ of 99.9.

Figure 12.1 Association between mean childhood IQ and desire for parenthood at 23: women (NCDS)

The picture is identical among men. Those who do not want to have any children at all have a mean childhood IQ of 104.3 whereas those who want some children have a mean childhood IQ of 100.0. The differences between the two categories of NCDS respondents are highly statistically significant among both women and men.

Figure 12.2 Association between mean childhood IQ and desire for parenthood at 23: men (NCDS)

However, once I control for whether currently married, whether ever married, religiosity, religion, income, education, social class at birth, mother's education, father's education, and number of siblings, childhood IQ has a significantly negative effect on the desired number of children only among men, not among women. Among men, childhood general intelligence still has a significantly negative effect on the desired number of children at age 23. No other variables have any significant effect on the number of desired children for men.

Among women, the number of siblings has a significantly positive effect on the desired number of children. The more siblings the women have themselves, the more children they want to have. But childhood general intelligence no longer has a significant association with the desired number of children once all the social and demographic factors are statistically controlled.

However, even net of the same social and demographic factors, childhood general intelligence has a significantly negative effect on the desired parenthood—whether they want to become parents or remain childless—both among men and women. More intelligent men and women are significantly more likely to want to remain childless than less intelligent men and women.

So it appears that general intelligence makes a difference only in the decision to become parents or not for both sexes. Less intelligent individuals are significantly more likely to want to become parents, and more intelligent individuals are significantly more likely to want to remain voluntarily childless. But, beyond that, only less intelligent men, but not less intelligent women, want to have more children than their more intelligent counterparts. Childhood general intelligence significantly predicts the value for parenthood for both men and women, but the value for children only for men.