> Bit of a tangent but, basically everything I ever I believed I understood about the nature vs. nurture argument have broken down completely in the face of raising (fraternal) twins.

I read something speculating that a major contributor to Americans' general disbelief that family members are usually very similar to one another is that most of their exposure to "family members" is actually to the members of fictional families on television who are played by unrelated actors.

(I know you're making an observation about how clear the differences between your children are. But I submit that if you compare them to a few unrelated children, you'll find that they are indeed very similar to each other overall.)

We have a lot of public pronouncements about what children, or people generally, are like, but almost all of it is completely uninformed by facts or experience.