If you liked, you could look at historical Western culture as well. In the 1800s, both boys and girls wore white, and gender differentiation in clothing style was quite subtle for the first few years of life. Styles only began to diverge around 1900 and the pink / blue dichotomy only became really prevalent after WWII.
That doesn't prove all gender preferences are cultural, but color choice certainly seems to be.
I was browsing a book on etiquette published in 1905 a while back and stumbled across an interesting mention that "a parent couldn't go far wrong following the standard conventions and dressing a girl baby in blue and a boy in pink"; it stuck with me and I have been wondering when the conventions changed the other way around. [The quote is from memory and probably not exact, and I can't check it, because I can't remember the book's title.]
That doesn't prove all gender preferences are cultural, but color choice certainly seems to be.