The old nature vs nurture! I'm also curious about this and I have a fairly good chance at gaining some anecdotal insight!

A family member who I'm very close with was adopted from South America. He doesn't speak Spanish, but had managed to find his biological family. He wants to visit them sometime, and had asked me to come along as a translator.

Will be interesting to see how similar he is from his biological siblings, in terms of personality. I've gotten the impression his biological family is quite poor, and he was raised in one of the richest countries in the world. Cultures are very different too, Scandinavia Vs south America.

If nurture matters at all, he'll be different from his biological siblings. If not, we should be able to isolate a "awesome bro-dude" gene from his biological family's DNA.

Wouldn't that be cool?

When I was younger I was certain Nurture was everything. As I have gotten older, had kids, I have been sliding increasingly supporting the Nature end of the spectrum.