Has anyone here ran a game with or played a PC that was in an incestuous relationship with another PC or NPC and if so, how did it turn out? 
No characters of mine have
consummated incestuous ideas. However, ages back I played a high elf that was a member of a noble family, they were all very concerned with keeping the bloodlines pure, yadda yadda. He actually became an adventurer to make a name, reputation and fortune for himself outside of what he'd inherited through no achievement of his own, to win the respect of his first cousin (who already returned feelings for him, but didn't think he'd proved himself a man suitable for marriage yet).
Amusingly enough, though the character was an excellent archer on paper, blind bad luck ensured he couldn't hit the broad side of a fat guy. It rained natural 1s any time he started attacking, regardless of what d20 was used to roll the attacks. When we weren't making cracks about the custom spell
Cerentil's boomeranging nerf arrow, the players attributed his ineptitude to genetic defects from generations of inbreeding.
