>>3535416While that guy is full of shit, there are some pre-modernization cultural practices that seem very incesty-y common across Northeast Asia (Korea, Japan, Northeast China). I don't have the study handy, but it used to be common practice for Manchu mothers to fellate their prepubescent sons. In Korea and Japan mothers and village women would often fondle or kiss the genitals of prepubescent boys (who would be running around naked or bottomless most of the time). This was common in rural areas as late as the 1960's. While it appears sexual to us today (and is sexual if you are a literalist) this sort of thing was meant to be affectionate and encourage growth/virility, and did not represent a desire to engage in coitus or participate in a relationship as man and woman (which most actual incest does).