I think those who are defending this topic are failing to see the forest for the trees.
I agree with those here as far as seeing other family members naked is not the equivalent of incest. Although it may not be what I grew up with, there are many families that are comfortable with nudism for non-sexual purposes and I find nothing wrong with it.
However what clearly is borderline (if not over the line) is any swapping of stories focusing on the body parts of those relatives, especially in an aroused state (I.e. erect), asking others to describe the details of their naked fathers, brothers and sons and admissions of masturbating or having sex in front of other family members (especially their own children). All examples which have been posted unchallenged many times here within various threads.
So let's not pretend the majority of the posts here on this subject are talking about the first example of recreational nudity rather than the incest fantasies of the latter. Let's also not use pretzel logic to try to deny the fact these many posts are getting around the 18+ TOS by not mentioning a specific number value when it's clear they occurred (or are still occurring) prior to the posting criteria. To think that the vast majority of these posters are talking about present time and only seeing their family members' dicks for the first time as a young or even middle aged adult still living at home is the height of naivety.
So while I think the OP could have worded things better (although given his history of being provoking under two different names now, it's not unexpected), I believe he was just trying to communicate the frustration and revulsion felt by some here when constantly seeing these redundant threads that are clearly not describing non-sexual nudism come up.
So again, merely seeing family members nude = not incest. Fixating on the specific sexual organs on those same members and describing them to others to satisfy their kink = incest. Whether actual contact occurred or not or what the dictionary says is irrelevant.