All psychological traits are heritable. This is best replicated finding in all of behavioral genetics. Some recent numbers include: I used to have a m

It’s perfectly valid for a trait to be more than 100% heritable

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2021-07-15 21:00:07

All psychological traits are heritable. This is best replicated finding in all of behavioral genetics. Some recent numbers include:

I used to have a mental model something like this: Each person has some number of religiosity points that comes from genes and some number that come from the environment. If religiosity was 40% genetic, I pictured this:

The problem with this picture—aside from being completely wrong—is that it suggests heritability is an immutable constant, like the number of chromosomes in a cell or the fine structure constant.

So what is heritability? It’s the ratio of the genetic variance of a trait with the total variance, including all causes. Since the environment is always changing, so is heritability.

The only math we’ll use is the concept of variance. If you’re not familiar with that, just think of it as “how variable” something is. Humans have high variance in how much we like folk music, but low variance in our number of fingers.

One note on terminology: Biologists use “phenotype” to refer to what actually happens, including all genetic or environmental causes. The phenotypic length of your foot is, thrillingly, the actual length of your foot.