My oldest son 10 plays entirely with boys, and his twin sister essentially entirely with girls. Their interests are also very stereotypical, and have been since they were very little -- back then we were put trucks and dolls down in between them just to see what they'd play with.

Perhaps this is partly a boy-girl twin thing.

Their younger brother 8 has some girl friends at school, but even he gravitates more towards boys and typical boy interests.

At all schools the kids have been at, there has been a lot of gender self-segregation in play, at least since K.

I'm interested that it not so for so many respondents. I wonder if people are less likely to reply if their answer is more in keeping with stereotypes.