Board Thread:Off Topic/@comment-25266931-20161119192054/@comment-14138255-20170318021804

Incest is frowned upon for 1. Being generally weird, and 2. Carrying a MUCH higher risk of genetic defects (which explains Joffrey, but not Tommen). 2nd/3rd cousin onward is generally considered safe on the defect end, but not so much the social end.