I've done a non-scientific, non-thorough experiment by advanced searching 'gender disappointment' (and ignoring the ones whinging about the term itself)
My tally is.
Second child, hoping for one of each, has 2 boys.
Second child, husband hoping for girl, has 2 boys
Third Child, has 2 girls, hoping for boy
Second child, having a second boy, she doesn't mind, everyone else commenting about pity it's not a girl
First child, terrified of disappointment, doesn't say what she wants
3 boys, disappointed there's not a girl.
So I'd say that it's less a preference for girls, and more a disappointment if you don't get at least one of each.
Perhaps you have some unconscious bias going on? Like how people think women are talking too much once they go over 30% of the conversation.