Childhood surroundings matter more than genes for would-be inventors

ARE inventors born or bred? Using tax, patent and academic records, a new study by a quintet of economists follows the lives of 1m American inventors in exceptional detail, including their parental circumstances, the neighbourhoods they grew up in and the colleges they attended. It shows that there are vast differences in the backgrounds of inventors measured by income, race and gender. Children born to parents in the top 1% are ten times as likely to grow up to file a patent than those born to parents who make less than the median income. Boys are four times as likely as girls to grow up and file a patent, while white children are three times as likely as black ones to do so. These data may lend themselves to a fatalistic view of innovation, but the authors provide strong evidence that a child’s surroundings matter more than his genes.

To tease out this point, the economists used third-grade test scores in New York City public schools as a rough measure of innate ability. Using maths scores (reading scores are useless for predicting future patent-holding), they show that even among the brightest pupils, those who are low-income, black or Hispanic are much less likely to go on to be inventors despite having the brains for it. This measure of intellectual prowess can explain just one-third of the gap in invention rates between high-income and low-income children—and virtually none of the gender gap. But as children get older, the gap in test scores becomes more helpful in predicting future inventors. “What the data suggest is that low-income kids, minorities, women start out on roughly equal footing to high-income males from non-minority families, and they gradually fall behind over time,” says Raj Chetty, one of the study’s authors.

Most studies suggest this is down to worse schools and rougher neighbourhoods. But the authors marshal strong evidence for a different mechanism: early exposure to innovation, and to inventors themselves, seems to matter a great deal. Children with patent-holding parents are disproportionately likely to become inventors too. Moreover, children of patent-holding parents are also much more likely to hold patents in the same niches as their fathers, which suggests that inventiveness is not merely genetic. Even if inventive abilities could be transmitted hereditarily, they are unlikely to convey special powers in, say, building amplifiers as opposed to modulators. Although parents and inherited privilege matter significantly, neighbourhoods also seem to have a large impact on future invention success: children who grew up in Silicon Valley, for example, are especially likely to develop computer technologies—even if they eventually move away. Children are also likelier to develop inventions in the same specific fields as their parents’ co-workers and their patent-holding neighbours. The authors, who fret over the number of low-income or female “lost Einsteins”, suggest that boosting childhood exposure to inventors might be more effective than reducing marginal tax rates as a means of increasing economy-wide innovation.

Selective colleges, and ones where a higher share of students study technical disciplines, tend to produce more inventors. It should be no surprise then, that the colleges that produce the most inventors per student are MIT, CalTech and Harvey Mudd, three of America’s most competitive engineering schools. But again, factors beyond raw ability seem to matter. The college which produces the fourth-highest share of inventors in the data set is little-known Kettering University in Flint, Michigan—edging out brand-name institutions like Stanford and Carnegie Mellon. This despite the fact that their students enter with much lower SAT scores and parental wealth. Robert McMahan, Kettering’s president, who himself holds five patents, credits the university’s unique history (until 1982 it was part of General Motors and retains deep ties with the car industry) and its requirement that students repeatedly alternate between classrooms and job rotations.

The relationship between environment and inventiveness appears to be different for boys than it is for girls. Average incomes and racial composition explain around 30% of the variance in patent rates across metropolitan areas for men, but only around 10% of the variance for women. Finding the right mentor seems to make all the difference: Mr Chetty notes that girls were only more likely to become inventors if they grew up in areas with lots of women inventors (and likewise for boys and male inventors). If young girls were exposed to the same number of female inventors as boys were to male inventors, the authors calculate, their invention rates would skyrocket by 164%, knocking out 55% of the gender gap. Economists reckon that long-run growth is caused mainly by technological change, and not shifts in labour or capital. The best policies to spur innovation, it seems, may have as much to do with mentorship as money.

• “Who Becomes an Inventor?” Alex Bell, Raj Chetty, Xavier Jaravel, Neviana Petkova and John Van Reenem. Equality of Opportunity Project. December 4th, 2017.