I'm aware of this effect, and the reason I think it doesn't apply is this: the children play with each other, but they are raised in separate households. (Slopp

I'm aware of this effect, and the reason I think it doesn't apply is this: the children play with each other, but they are raised in separate households. (Sloppy writing on my part, I wrote "children of the family are young they play and do everything together" which was an exaggeration. My bad.)