Parents are naturally excited about who the person they're creating is going to be. Any detail is made much of, but basically all you know before the kid is born is the fetal sex. In many places, notions of gender are changing, and some parents are not forcing their kids to comply to a specific gender based on their chromosomes. But not in many places.
In fact, many parents try to force gender roles on their babies before they've even taken a breath of air. Twitter user Onson Sweemey tweeted a collection of gender reveal cakes—these are cakes that parents cut to reveal the sex of their baby, either to one another or their guests at a baby shower. They're usually a specific color—blue or pink—on the inside to indicate whether the baby is a boy or girl. And some of the metaphors used are pretty wild.