Wait, flesh this thought out? Twin studies were the dominant methodology of the 1970s-1990s, until molecular genomics --- and genetic studies with controls for family relations demolished their heritability estimates. You just wrote a sentence that implies a straight line of progress on understanding this (weirdly, giving a 70s-vintage point in one direction along with a 2010s-vintage point in the other), but it's the opposite (there's a whole thing about this, the "missing heritability problem").

"Go look up twin studies" is a very strange thing to tell someone on a message board in 2026. It's like saying "go look up phlogiston".

“Controls” for familial wealth have mostly been debunked by any kind of basic statistical analysis.