I don't know if you've ever had any food issues or sensitivities, so you may know this, but they can be very serious. There are textures I can't eat without literally gagging, for example -- it's not something I can control. So I can well imagine that if this person has something like that going on, and her parent is being so insensitive about it, she joked in a way that was intended to sting.

I also think it's possible that she spoke what feels like the truth. Not being listened to, not being believed, when you have an issue like that -- it can be devastating, and for someone to just expect you to lol get over it for their convenience is... well. And if that person just won't fucking let go and let you eat when you are eating (note that she brought this up over dinner), I can see why the child in this scenario would blow up.

I really disagree with you that the food thing is necessarily a "smaller" thing that's "easier" to fight over. Eating disorders and difficulties with certain flavours and textures can be huge. Please don't be dismissive of that.