So if sex within the clan is incest, what are the consequences when it inevitably happens (we're talking about people here, after all). Initiated unmarried teens who hardly see people outside the clan for most of the year, for instance – I'm hard-pressed to believe that they manage to keep it in their pants. Is it merely a minor crime (even Medieval Europe was surprisingly lenient when it came to pre-marital sex)? If it's a chaotic activity, one has to wonder how it's not a huge problem – it would seem far more common than other chaotic activities like rape or secret murder.
Or if between married people within the clan – would it be worse than the 'mere' adultery (in quotes because adultery is a pretty big deal in itself), a further aggravating factor?
(One also has to wonder exactly what counts as 'sex' – only potentially procreative heterosexual acts? "I did not have sex with that clan-member"?))