I think you need to read up a little more on behavioral genetics. To point out the obvious, besides adoption studies (you might benefit from learning to use Google Scholar) and and more recent variants like using sperm donors (a design I just learned about yesterday), your classic twin study design and most any ‘within-family’ design does control for parental actions, because they have the same parents. eg if a trait is solely due to parental actions, then monozygotic twins should have exactly the same concordance as dizygotic twins despite their very different genetic overlaps, because they’re born at the same time to the same parents and raised the same.
More importantly, the point of GCTA is that by using unrelated strangers, they are also affected by unrelated parents and unrelated environments. So I’m not sure what objection you seem to have in mind.
Sorry if I’m misunderstanding the method, but doesn’t it work something like finding strangers who have common genetics by chance?
If so, then 2 jews are more likely to have common genetics than chance, and also more likely to be circumcised. So it would appear that circumcision is genetic, when in fact it’s cultural.
It works by finding common genetics up to a limit of relatedness like fourth-cousin level. I think some Jewish groups may be sufficiently inbred/endogamous for long enough periods that it might not be possible to run GCTA with the usual cutoff since they’ll all be too related to each other. Population structure beyond that is dealt with by the usual approach of subtracting out 10 or 20 principal components and including them to control for that. This is a bit ad hoc but does work well in GWASes and gets rid of that problem, as indicated by the fact that the hits replicate within-family where the population structure is equalized by design and also have a good track record cross-racially/country too: https://www.reddit.com/r/science/comments/4kf881/largestever_genetics_study_shows_that_genetic/d3el0p2
I think you need to read up a little more on behavioral genetics. To point out the obvious, besides adoption studies (you might benefit from learning to use Google Scholar) and and more recent variants like using sperm donors (a design I just learned about yesterday), your classic twin study design and most any ‘within-family’ design does control for parental actions, because they have the same parents. eg if a trait is solely due to parental actions, then monozygotic twins should have exactly the same concordance as dizygotic twins despite their very different genetic overlaps, because they’re born at the same time to the same parents and raised the same.
More importantly, the point of GCTA is that by using unrelated strangers, they are also affected by unrelated parents and unrelated environments. So I’m not sure what objection you seem to have in mind.
Sorry if I’m misunderstanding the method, but doesn’t it work something like finding strangers who have common genetics by chance?
If so, then 2 jews are more likely to have common genetics than chance, and also more likely to be circumcised. So it would appear that circumcision is genetic, when in fact it’s cultural.
It works by finding common genetics up to a limit of relatedness like fourth-cousin level. I think some Jewish groups may be sufficiently inbred/endogamous for long enough periods that it might not be possible to run GCTA with the usual cutoff since they’ll all be too related to each other. Population structure beyond that is dealt with by the usual approach of subtracting out 10 or 20 principal components and including them to control for that. This is a bit ad hoc but does work well in GWASes and gets rid of that problem, as indicated by the fact that the hits replicate within-family where the population structure is equalized by design and also have a good track record cross-racially/country too: https://www.reddit.com/r/science/comments/4kf881/largestever_genetics_study_shows_that_genetic/d3el0p2