There is a certain decorum here, not to do with age, maybe it is the subject, would it be as "gentile" if the subject were Transformers, comic books, dungeons and dragons etc.? don't know, I have been close (I have children) to some of these, and they are not as nice. We, of a certain age group, were taught to communicate verbally, which, in most cases, did not include the easily used crutch of conversation cripples, profanity. Not to say that there have not been a few "F Bombs" uttered, even shouted from these lips, but very seldom , if ever, in mixed company.
To sum it up, the decorum is based on a certain level of unspoken expectation, can't give you an example of it, but it is here.