Category: Louis Browning

Human Biology News: Social Mobility Genes Identified

It’s all in the genes…or at least some of it is.

Dr. Belsky and colleagues matched the genotypes of Dunedin Study participants with the genome-wide associations with educational attainment that had been reported previously. The results revealed that genetic links with educational attainment predict outcomes that go well beyond the completion of schooling, as Dr. Belsky and colleagues hypothesized. 

Details of the Duke study appeared June 1 in the journal Psychological Science, in an article entitled, “The Genetics of Success: How Single-Nucleotide Polymorphisms Associated With Educational Attainment Relate to Life-Course Development.” The study reported five main findings. 

1. Polygenic scores predicted adult economic outcomes, even after accounting for educational attainments.
2. Genes and environments were correlated: Children with higher polygenic scores were born into better-off homes.
3. Children’s polygenic scores predicted their adult outcomes even when analyses accounted for their social-class origins; social-mobility analysis showed that children with higher polygenic scores were more upwardly mobile than children with lower scores.
4. Polygenic scores predicted behavior across the life course, from early acquisition of speech and reading skills through geographic mobility and mate choice and on to financial planning for retirement.
5. Polygenic-score associations were mediated by psychological characteristics, including intelligence, self-control, and interpersonal skill.

Of course the major question: does this differ between population groups? 
What about all the hand-waving about “the associations are small?” 
Three points: 
1. Additional studies may uncover new genotype-phenotype associations that increase the fraction of the “social mobility phenotype” influenced by genes.

2. Even if the associations remain small, these small effects need to be multiplied over large numbers of people, particularly if differences exist between population groups, and over evolutionary time, and one will therefore likely see important large scale gene-based behavioral patterns emerging at the mass level, based on these “small” associations. 

3. Point #2 of the paper is key: the correlation between genes and the environment. 
Even if the genetic influence is “small,” that influence can alter the environment and that environmental change can not only directly affect phenotype, but can further select gene frequencies. Therefore, a positive feedback loop between genes and the environment, connected through resultant phenotypes, can be established even with “small” associations. Those associations “get the ball rolling” and the effects are amplified; the “better off homes” noted by the authors are the result of the parents’ genes and those of the surrounding population.

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