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Shared environment is probably not created equal though. While the family environment is constant, parents are likely to vary (deliberately and/or not) in their

Shared environment is probably not created equal though. While the family environment is constant, parents are likely to vary (deliberately and/or not) in their resource allocation (e.g., attention and care) among their kids. An interesting recent paper shows that the non-inherited genetic material of the parents may _still_ have an influence on the kid. [0] What exactly accounts for that influence remains to be elusive, and it would be quiet astonishing if the majority of the influence can be explained by well-established (or rather, exhaustively studied) behavior patterns in psychology. For example: birth order, number of same-sex siblings etc. [0] https://www.biorxiv.org/content/early/2017/11/14/219261 https://www.biorxiv.org/content/early/2017/11/14/219261

gwern 9y ago
> An interesting recent paper shows that the non-inherited genetic material of the parents may _still_ have an influence on the kid. [0] Yes, but that comes out of the heritability component, not the non-sharedenvironment component. > For example: birth order, number of same-sex siblings etc. Birth order, by definition, can't explain any of the variance in fraternal vs identical twins, and there's a lot of doubt about whether it exists at all and for which traits. Likewise, I haven't seen much credible research on sibling effects - most such sociological research doesn't even bother to try to control or quantify any of the relevant genetics, and is 100% useless.