The Living Thing / Notebooks :

Nature, nurture and friends

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

See also

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 question: When does asking, e.g. “which is more important, nature or nurture?” gain us a useful perspective, or research question? Never. You need to refine it. 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?”, or if I tried to represent the “contribution” of “hardware factors” versus “software factors” to “word processing” via a variance decomposition? We could surely extract some nontrivial correlations from that, but it would be hard to argue we were approaching this analysis with the most effective tools. Worse, imagine that we had to pick “sides” and choose which one was “more important”. Anyway, you get the drift. Careful here.

If we make it mathematically precise and ask “What is heritability score of X?”, where X is some policy-relevant behaviour, we are not necessarily thinking about anything interesting because the mathematical definition of heritability itself may not do what we intuitively would like it to.

Note also care with which metrics are chosen for heritability studies. Homework questions: How heritable is English vocabulary size? How heritable is bank balance? How heritable is a bachelors degree in social psychology?

Heritability scores are indeed one sciency projection of this debate:

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: