That's not too unique that is just unbelievable. BTW, 76 times removed would be a person from 76 generations away... A century usually has 4 or 5.
As people have said, I think a lot is in the execution. In the short story "A dry, quiet war", by Tony Daniels, the main character is outrageously badass. Like, more hardcore than anyone. Ever. And it's believable and completely un-Mary Sueish because of the skill with which it's executed. If you're worried about this specific character you could always give her normal hair, I suppose.
Thanks. I'm thinking I need to balance out the more unusual straights among the other main characters, though, so the narrator doesn't seem like the oddball of her family or something. Like giving the brother the unusual hair (although obviously it wouldn't be waist-length ringlets, lol.) instead.