Our Genetic Lottery

I need to figure out what behavior genetics means for an egalitarian society

It has been a couple of weeks since I was last in your inbox and this is because I’ve been struggling to grapple with my recent inquiry into behavioral genetics. Last month, I wrote a short introduction to behavior genetics in which I introduced the work of Robert Plomin and his long career of genetics research which uncovered the large impact that our DNA has on who we are now and who we will become. For example, according to his data, 50% of the difference in IQ scores between people can be accounted for by genetic differences.

However, Plomin’s discussion on what this means for our society’s view on equality left a bad taste in my mouth. For example, here is what Plomin says about the implication of genetics research on equal opportunity (emphasis my own):

What look like systematic environmental effects in fact reflect genetic differences. For example, the socioeconomic status of parents is correlated with their children’s educational and occupational outcomes. This correlation has been interpreted as if it is caused environmentally. That is, better‐educated, wealthier parents are assumed to pass on privilege, creating environmentally driven inequality in educational opportunity and stifling what is called intergenerational educational mobility.

Genetics turns the interpretation of this correlation upside down. Socioeconomic status of parents is a measure of their educational and occupational outcomes, which are both substantially heritable. This means that the correlation between parents’ socioeconomic status and their children’s outcomes is actually about parent–offspring resemblance in education and occupation. Phrased as “parent-offspring resemblance,” it should come as no surprise that genetics largely mediates the correlation. Parent-offspring resemblance is an index of heritability, and heritability is an index of equal opportunity. So, parent-offspring resemblance for education and occupation indicates social mobility rather than social inertia.

Plomin calls heritability an “index of equal opportunity” which is to say that disparity can be justified as long as the difference is due to genetics and our “non-shared” environment1 (see footnote for definition).

For those of us that care about creating a just and equal society, we are left with our hands-tied—what can be done? Should those that lose the genetic draw simply be left behind?

It’s also true that genetic differences between people have been used to justify the most heinous and evil crimes in human history so I tread carefully when I think about genetic difference and what it means for all of us. Left-leaning politics has historically tried to downplay genetic difference in an effort to pursue egalitarianism, but the science is clear: genes don’t determine how our life comes out, but they definitely make a difference.

This is why I am pleased to discover Kathryn Paige Harden’s new book The Genetic Lottery: Why DNA Matters for Social Equity. In it she hopes to make the case the genes matter and that we can still achieve the egalitarian society that should be desirable in our modern world.

It’s always fun when I discover two books that can agree on a lot of the facts but come to different conclusions about what we should do about those facts.

What do you think? If we accept that genes matter a lot, what should we do about it when thinking about inequality? I understand that this can be a politically-loaded question but I’m nonetheless curious to hear your thoughts, so comment below!

Until next time, thanks for reading and taking this journey with me.

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P.S.S. Many of our have joined our community since my last post, so I wanted to briefly re-introduce myself. My name is Clayton and I am currently a first year MD/PhD student. In my free-time I read widely about modern neuroscience and other topics related to the human experience. Synapse is the brain-child of that effort as I enjoy sharing with people my thoughts on such topics as free will, morality, and (recently) genetics. You can check out more of my most popular essays here. I love connecting with readers, so feel free to reach out by replying to this email!


Our “non-shared” environment are the random, unsystematic influences in our lives (i.e., NOT parenting, schooling, job environment, etc) which Plomin claims accounts for the rest of the disparity between people. Our “non-shared” environment is NOT our “nurture” but rather chance events that don’t correlate between people.