Oh, fuck, I know someone this happened to, but transmasc.
He was all hyped to start T, ready to really shape his body and such.
Two years in, he's at a get together, and we're talking about some of the little stuff he'd been learning about the male experience, and he leans in, "and nobody told me I'd fucking look like my dad, damn it".
And he did, he so did. There's a family pic of them on Facebook, and it's like twins, except one has more gray hair than the other. Earlier pics, you don't notice it except around the eyes, but after maybe six months on T, it gets so obvious.
Next time I ran into him, I was all "hey, Mr their last name, how's your son?" The punch was worth it :)