[mjburgess]

Gentle reminder: heritability isnt what "most people think it is".

It's just covarience with genes -- this might seem like it means "X is genetic" -- but it *doesnt*. Consider accents (eg., the scottish accent) this is highly heritable: typically only people with the genetic profiles of those localised to scotland have it.

Consider using heritability to determine genetic vs. envrionmental causation (largely: you just cant use it to do this). Eg., even in the case of height: it would seem that the genes of people in poor-nutrition countries were the cause of their low height.

The movement from "heritability" to "genetic causation" *asssumes* (and always, by assertion *assume*) that the trait studied is already genetically caused. IF we know this, THEN hertiability is a somewhat reliable measure of "to what degree".

But in almost all cases we have no grounds whatsoever to independently assume this. Rending most heritability studies basically useless.

[joshink1]

Thanks for that info.

A quick aside:

I'm curious why it's gene vs environment (either/or), and not gene + environment (emergent)? If the latter, then I'd think heritability would necessarily factor both genes and environment -- as genes don't express in a vacuum.

For example, the heritability of "general skin cancer risk" is both genetic (melanin) and environmental (latitude, sun irradiance...). Due to differences in UV exposure, the genetic influence is probably greater at lower latitudes than higher.