The preponderance of terms like "girldad" and "boymom" among cis people offers a clue into parental transphobia: they literally see their children's gender a part of their identity. "Well actually you're the one forcing me to take on an identity I don't want" is a DARVO, but it's a darvo supported by normative ideas of how parenthood should function.
but yeah i think this kind of thing is why gender reveal parties feel kinda gross to me. well, that and the explosions and wildfires