Long before there was "help me stepbro!", there was "have you ever seen your mom naked?". The difference? People wouldn't (normally) contaminate a box of Kleenex's finest to radio shows. Social media was and still is our biggest evolutionary mistake.
At this point, self-aware cousin fuckers really deserves their own sub-genre. Decades of inbreeding and limiting toothbrush ownership to 1-per-household has carved itself into a niche that I can only describe as recession proof Walmart porn. Ohio sends it's regards.