Nature, nurture and friends

If life gives you lemons, what should you make?

Nature! Nurture! Another distinction that sounds like it might represent something Fundamental And Real. Seems to have largely supplanted Calvin’s distinction between total depravity vs penance in the people-blaming niche.

I do not have much interest or expertise in this area, but this placeholder will collect a couple of interesting links to refer to next time I get caught up in some aggravating muddy-thinking semantic argument in this area.

See also other quirky taxonomies:

  • mind/body
  • free will/determinism
  • good/evil
  • masculine/feminine
  • salt/pepper
  • Mac/PC
  • Gryffindor/Slytherin/the other ones
  • sugar, spice, all things nice/slugs, snails, puppy dogs’ tails
  • Doctor Who/Daleks

Unlike Doctor who/Daleks, this one is used for actual decision making and public debate outside of Tumblr, so it bears looking in to.

Questions to consider before engaging in discussions of heritability.

First aside. I think we can rule out the usefulness, of the question “which is more important, nature or nurture?” as a useful one. We need to refine it to get to an answerable question. That should go without saying, you would have thought, but pub conversation suggests not. To recycle a common analogy, imagine a computer science where the central questions were ones like: “can do word processing on my laptop because of hardware or because of software?”. This kind of muddy thinking will have us trying to discern the contribution of “hardware factors” versus “software factors” to word processing via a variance decomposition. Not that variance decompositions happen in the pub conversations usually.. Anyway, you get the drift. Careful here.

Similarly, if you want to pick an established definition of heritability it would be wise to clarify what assumptions it entails.

Heritability scores

The classic heritability score, is an good case study.

Spoiler: Heritability is a linear variance decomposition over two factors, and thus is a blunt instrument with which we can bash results out of meagre data and computation. A lot of, e.g. the twin studies are constrained by lack of data, because of a lack of twins. This might change with advances in genomics. Or not.

As with any research that comes from observational studies, one should be suspicious reading research that doesn’t at the bare minimum extend their method to a causal DAG. It is easy to find papers that don’t.

Homework questions for classic heritability scores:

  1. How heritable is English vocabulary size?
  2. How heritable is bank balance?
  3. How heritable is a bachelors degree in evolutionary psychology?


  • Ozymandias, Shared environment effects are eal makes some interesting points about how we discuss shared environment.

    Believing in zero role for shared environment also fails to pass the sniff test. Lots of people, I think, will agree that whether or not you talk to your baby might not have any long-term consequences. But the “zero role for shared environment” position requires yourself to commit to the position that all of the following have either zero correlation between siblings or no effect on children’s psychology whatsoever:

    • Lead poisoning.
    • All other forms of air and water pollution.
    • Prenatal nutrition.
    • Drinking during pregnancy.
  • Scott Alexander parodies The Gattaca Trilogy

  • Jeffrey Lockhart, Blueprint for what in a fairly adversarial review of an evolutionary psychology book, covers some of the weak-manning that happens in this debate.