Most studies that try to separate genetic factors from “nurture” factors provided by the parents will twins that were adopted separately. It’s a small-ish subject pool though, and probably not recent since I don’t think they encourage separating siblings for adoption now.
Most studies that try to separate genetic factors from “nurture” factors provided by the parents will twins that were adopted separately. It’s a small-ish subject pool though, and probably not recent since I don’t think they encourage separating siblings for adoption now.
Did they ever encourage it?
It definitely used to happen a lot, judging by the sample size in twin adoption studies (usually 200-something pairs of separated twins).