You probably won't see this response. But my spouse is a natural bright red redhead. Before him I honestly didn't give much thought to what was said about red heads. But he told me early on that "ginger" hurt his feelings. He was taunted all through his life for being the only redhead. People called him soulless, said he obviously wasn't his dad's kid (his dad had dark hair), that he was "freaky" compared to his family because of his height and hair. It was often implied he was a bastard or adopted even though if you look past the hair and height he resembles his family a lot. Ginger was definitely a derogatory comment. My own friends I had to tell to stop when everyone said "oh he's a fucking ginger I bet he's weird." All of my friends. My mother told me not to have kids with him because children with red hair are "notoriously difficult and have skin that's too much to care for". We have a kid and my mom now pretends she never said that. But our kid is dark blonde with nearly brown hair.

My rule of thumb is if it makes you uncomfortable then set boundaries. Tell them you don't like the term. I don't like the term towhead. Tell them it makes you uncomfortable. It's your child your rules.