Not much bother me either. But if author without warning or mention immediately changed hair color, in one AVN something was like that - then i completely didn't understand why he did that. then that concern me.
Why then i can't go barbershop and change dyed color in 3-4 options - for underline sexuality, or change character of heroine
I would always prefer the same hair color but if it's female MC getting it on with mom or sis, I couldn't care less coz I'd just be grateful for such rare content.
I think the devs are trying to cater to as many people as possible. You like blondes? Got you covered, redhead? You came to the right place. Me personally, I think the “family” looking somewhat similar is the way to go. It helps make the story more compelling when you can actually believe the characters are related
Hair color doesn't really bother me unless it's something like rainbow colored. I'm more concerned about the length of the hair, too short and I'm out.