The Effects of the Shared Environment on Personality

There is very little in the upbringing of parents of kids with a new family that makes the kids more similar in their personality, right? Beyond the effect of the genes and so on. And I do think that is very puzzling for many people because they do assume that the parenting does have like massive effects across siblings as well. That's just an example of this self-fulfilling lay assumption that we should not treat our children differently.