Serious question

Why do parents act like grandkids are such an inconvenience to them? We’re at a family reunion and my mom took it upon herself to get on the subject of me being pregnant. I eye rolled as soon as she brought it up bc I knew where it was going. She goes into “well my daughter is pregnant with a little girl and already has a little boy so now she has one of each and can stop having kids” then she starts talking about how young I am (I’m 24) then other people chimed in to agree that that’s too young. Like what tf that’s not even young. I’m engaged to the father, we have our own house, our own cars and we dont need my family for anything so I’m not sure why she always makes comments about how she wishes I’d stop having kids.