Income & children

Interesting paper I found Sex, status, and reproductive success in the contemporary United States (PDF). Since you can read the whole paper, I won’t summarize it for you, but below the fold is a graph that some might find of interest.


  1. What’s the highest income bracket: 1 or 21?

  2. 21.

  3. Only low income females are above replacement. 
    I wonder whether illegitimate children were assigned to their fathers correctly. That would be hard to get data about. The data are pretty old, but illegitimacy was pretty high in 1994 I think

  4. You see, most blokes income will max out at 20. You?re on 20, all the way up, all the way up…Where can you go from there? Nowhere. What we do in the US, is if we need that extra push over the cliff…21. One more. Then you are really rich”

  5. Since women still tend to be the primary caregivers, a woman’s income is a proxy for the income she foregoes (opportunity cost) by having lots of kids. So I see no surprise there. The male can support more children with higher income. The opportunity cost effects would tend to be low as the male does not usually stay at home with the kids. 
    She tests for frequency of sex as some sort of precursor to the number of kids – which seems odd in today’s birth-controlled society.  
    The article is pretty short. No race or cultural variables that I can see.

  6. They’re mining the same data as Inductivist and Half Sigma I see. The inverse correlation between intelligence and frequency of sex was already mentioned by HS… 
    Anyway, result is none too surprising, but it’s always nice to have more datapoints. 
    Also, can’t resist noting that my wife and I have just recently surpassed replacement with the birth of our third :-)

    congrats! the future is in your genes!

  8. Income is probably a proxy for IQ 
    Ian Deary had a paper in Personality and Individual Differences in 2004 showing that higher IQ women are less apt to get married. 
    Here is the abstract from that paper  
    The study examined the influence of IQ at age 11 years on marital status by mid-adulthood. The combined 
    databases of the Scottish Mental Survey 1932 and the Midspan studies provided data from 883 subjects. 
    With regard to IQ at age 11, there was an interaction between sex and marital status by midadulthood 
    (p = 0.0001). Women who had ever-married achieved mean lower childhood IQ scores than 
    women who had never-married (p < 0.001). Conversely, there was a trend for men who had ever-married 
    to achieve higher childhood IQ scores than men who had never-married (p = 0.07). In men, the odds ratio 
    of ever marrying was 1.35 (95% CI 0.98?1.86; p = 0.07) for each standard deviation increase in childhood 
    IQ. Among women, the odds ratio of ever marrying by mid-life was 0.42 (95% CI 0.27?0.64; p = 0.0001) for 
    each standard deviation increase in childhood IQ. Mid-life social class had a similar association with mar- 
    riage, with women in more professional jobs and men in more manual jobs being less likely to have evermarried 
    by mid-life. Adjustment for the effects of mid-life social class and height on the association between 
    childhood IQ and later marriage, and vice versa, attenuated the effects somewhat, but suggested that IQ, 
    height and social class acted partly independently.

  9. Related item via 2blowhards:

  10. the fact they only give the regression line (and not the actual data) makes me suspicious.

  11. bbartlog, I hate to be a downer, but replacement is 2.1 for a reason. So keep those kids alive!

  12. The graph alone is misleading, Razib. Spouses of rich men have also higher fertility. The article mentions that.  
    Also, the article goes against observed fact that higher educated people is less fertile than proletarians, who have more children.  
    I dont think the controversy is settled.

  13. Assortative mating is probably key to understanding the graph. High-income men are very willing to marry low-income women. But high-income women to a much greater extent want to marry high-income men.  
    As the number of high-income women has been rising, this effect probably also accounts for a significant share of the widening dispersion in family income. 
    Career women need to be encouraged to marry sexy, blue-collar men. I’m doing my part by looking for a rich girlfriend!

  14. Jeff 
    The graph is descriptive, not prescriptive. The universe is indifferent to human behaviour.  
    More than money, you should search for beauty.