>>280107667 (OP)You're wrong on both counts. Two people doing acts to each other consensually by default isn't immoral, and science doesn't enter the picture unless you're talking about breeding, but that's illogical since you can practice incest without creating babby. And even if you did make babby, it's still going to have better chances at not having defects than non-related retards or individuals with bad inhereditary conditions having kids, yet that's perfectly legal.
If anything it's a perfectly moral benevolent act to nut balls deep in your little sister as she wraps her legs around your waist and claws your back as she has a massive orgasm.