My dad was the youngest child of 9 (I think?) and was put up for adoption when his birth parents finally split up. Dad was the lucky one according to his birth siblings. I'd bet all my money he's HG+, though apparently his birth parents didn't show GTness. All this is pretty new, as Dad just tracked down the family a year ago or so.

Nurture doesn't cut it either, as he was raised in a simple farm family, the first to go to college (though 2 younger siblings in his adoptive family did follow him to college). No one else in the adoptive family shows signs of being GT at all.

Kriston