That definitely is the case with me (say in around 70% of cases?).
I think in my mind, people that are my type = attractive. I want to be attractive. Therefore, my ideal look = the body type I am attracted to. Thankfully, I have almost achieved my ideal "look" or whatever.
So yeah, I do look like people I have sex with usually.
I think I kinda did ten or fifteen years ago, but I'm a bear/dad now and I'm much more into rugged women than rugged men. My taste in men runs twink-ish, usually.
My wife has aged similarly though, which very much works for me.
That's fair, My taste in men also leans more towards twinks, and currently I look kind of twink-y. But maybe if I keep gaining weight and muscle, while I don't think I'll end up looking "bad", maybe I'll stop being my type.
I have a client who's SO's twin brother is not gay. I don't know what the odds are, of course, but this is proof that it can occur! I suppose it goes without saying they cannot be identical.
No, I like both men and women with dark hair/eyes/complexion and I look the complete opposite. I definitely have a type. Oddly, my brother, though straight, has the same preferences in women and he and I look alike.