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February 23, 2003

Intelligence: Genes Cause Environment

Okay-- here is a brilliant alternative to the nature versus nurture debate, from our hero Flynn with colleague Williams Dickens. Thanks to Stephen Fromm in comments in my Why IQ is a Moving Target post.

What if genes help people find better environments that reinforce small genetic advantages? This would encourage a cascade effect where, untended and uncountered by egalitarian social forces, those with small advantages would end up with disproportionate gains in abilities.

In their paper Heritability Estimates vs. Large Environmental Effects: The IQ Paradox Resolved, the researchers give this example:

Take those born with genes that make them a bit taller and quicker than average. When they start school, they are likely to be a bit better at basketball. The advantage may be modest but then reciprocal causation between the talent advantage and environment kicks in. Because you are better at basketball, you are likely to enjoy it more and play it more than someone who is bit slow or short or overweight. That makes you better still. Your genetic advantage is upgrading your environment, the amount of time you play and practice, and your enhanced environment in turn upgrades your skill. You are more likely to be picked for your school team and to get professional coaching.

Thanks to genes capitalizing on the powerful multiplying effects of the feedback between talent and environment, a modest genetic advantage has turned into a huge performance advantage. Just as small genetic differences match people with very different environments, so identical genes tend to produce very similar environments—even when children are raised in separate homes.

In other words, kinship studies of basketball, no matter whether they involved people with identical genes or different genes, would underestimate the potency of environmental factors. Playing, practicing, being on a team, coaching, all of these would be credited to genes—simply because differences in them tend to accompany genetic differences between individuals.

Flynn and Dickens seize on the idea of the "social multiplier" where society rewards small differences in ability with massive differences in social reinforcement.

As in taking small differences in SAT scores and telling those who score lower that they won't get to go to college or go to less well-funded schools with poorer teachers.

This goes to a core problem I have with the whole affirmative action debate. The issue should not be who gets to go to the best schools, but why we devote so much social funding in the US to those with the greatest ability. This is not a given, since other countries put far greater resources into vocational education and a range of skill-enhancing programs not aimed at university superstars.

But the US is fixated on a "winner take all" system of social rewards where every step of small success gets overrewarded, leaving those previously a step behind a mile behind.

Think about it: