Feb 13·edited Feb 13Liked by Emil O. W. Kirkegaard

I have three (somewhat) related questions about heritability:

1. Why do we use h^2(variance explained) and not "h"(correlation) with the breeder's equation? In other cases of regression towards the mean correlation is used right?

Is it because we have: parent phenotype (*h)-> parent genes (*1)-> child genes (*h)-> child phenotype. So regression towards the mean twice, h*1*h=h^2 in total?

2. Which mean is it that one actually regresses towards?

I've seen grandparent mean(would be unambiguous), family mean(what does this mean exactly?) and population mean(surely depends on how specific you are; White Americans or White West Virginians for example) mentioned.

3. I have seen a lower(0.5-0.6 vs the usual 0.8) heritability used with the breeder's equation with the explanation being that only additive/narrow-sense heritability matters for it.

Thanks for this Emil. I've been trying to meander my way towards an understanding of individual heritability, but I have never seen it explained so clearly. Will definitely check out the book that you recommended.

Emil, thanks for the somewhat deep dive into individual heritability. This subject is fought with misunderstanding, and you have helped clear it up.

Nice post.

edited Feb 13I have three (somewhat) related questions about heritability:

1. Why do we use h^2(variance explained) and not "h"(correlation) with the breeder's equation? In other cases of regression towards the mean correlation is used right?

Is it because we have: parent phenotype (*h)-> parent genes (*1)-> child genes (*h)-> child phenotype. So regression towards the mean twice, h*1*h=h^2 in total?

2. Which mean is it that one actually regresses towards?

I've seen grandparent mean(would be unambiguous), family mean(what does this mean exactly?) and population mean(surely depends on how specific you are; White Americans or White West Virginians for example) mentioned.

3. I have seen a lower(0.5-0.6 vs the usual 0.8) heritability used with the breeder's equation with the explanation being that only additive/narrow-sense heritability matters for it.

Make sense but then apparently additive heritability('A') is what is estimated in twin studies and that there's no non-additive genetic effects for intelligence(for example table 1 here: https://www.stevestewartwilliams.com/p/12-things-everyone-should-know-about).

So is additive heritability ~0.8 or lower at like 0.6?

edited Feb 14Basically natural aristocracy

Thanks for this Emil. I've been trying to meander my way towards an understanding of individual heritability, but I have never seen it explained so clearly. Will definitely check out the book that you recommended.