I took a Psych Intro class as continuing education a few years ago. I think if I remember correctly, the gender attraction stuff happens in two phases. One where kids recognize the difference between the sexes and then start relating with the same-sex parent. And another when physical and emotional attraction occurs. I believe that the second occurs during puberty for most kids...and that the first phase is more based on mirroring of adults.

I have a 2nd grade girl. I have found she "likes" boys. I don't think she realizes the diffrence. I have explained boys can be friends you don't have to "like" any boys right now! She seems to have learned alot from other kids at school. Also from my siblings because they are 20 and 16 so of course date. So I would totally beleive its just copying someone she looks up to.