I mean: you can definitely do whatever you want with your kids. But you should at least think about the fact that you are basically deciding how they should be. When you should only love them for who they are. It doesn't matter if they are a boy or a girl.
Not to be rude but You don't think that your challenge is sexist? You're not thinking about the gender of the babies but about their biological sex. Also you're practically saying that pink is just for girls and blue is just for boys.