just out of curiosity why would you feel different if it was a daughter?
It is not that I would feel dramatically different, but I think--and certainly historically this is true--men tend to have an emotional connection with their sons that they do not have with their daughters (women have a similar connection with their daughters that they don't have with their sons). This is a connection that cuts across timelines and virtually all cultures. If you are male, your son is a part of you--literally an extension of you--in a way that your daughter is not. I would no more give up my son than cut off my right arm. And I would do anything possible--legal or illegal--to retain custody of my male child. Is that sexist? Perhaps some would view it that way, but I would expect a mother to do the same thing for her daughter, and I would think it perfectly appropriate--not sexist or wrong.
There are some differences between men and women, but
different does not have to mean wrong, superior, or inferior. Think of it this way: when a woman gives birth, historically the one person she wants by her side during that moment is her mother. That is a special bond that mother's and daughters share. In modern times, fathers have been welcomed into the delivery room. I think that is great for couples who want to that, but it is
different from having a mother there. There is a unity between mothers and daughters that no man can ever understand, copy, or replace. A similar, but different, unity exists between a father and son and no woman can copy or replace it. Again this a very ancient idea that cuts across virtually all cultures; it should hardly need explaining. That said, obviously, there are a lot of "men" who do not feel very connected to their sons, have no qualms about giving up custody, or having some other guy raising and providing for his son--while he enjoys visitation rights. That could never be me.