I have a better relationship with my dd than my DS and part of that is their sex difference.
It's no use in putting your head in the sand and pretending the adult lives of men & women follow the same path- for most they don't. The irony of this question being on a site called mums net should give it away that women's lives are often very different than men's based on their biology at birth.
As far as my own experience goes I did lots of 'gender neutral' parebting with my 2. I still now have a DS who only wants to talk about computer games or football and a dd who is kind and caring in a way DS would never be.
In the future DS will most likely be earning more and may even have DCs I never meet. Dd will no doubt have the 'women's dilemma' of juggling work & family.
I can understand why some people want one over the other. Tbh I don't entirely believe people who don't have some slight preference.