Personally, I think the generation influence plays only a minor role in it. Yes, newer generations are more open/liberal as evidenced by a lot of things in our society (for example, amount of allowable cursing, and tolerance thereof, on public TV).
But there are also some side issues raised with being more open - IOW, what one may define as appropriate "openess" WRT sex, another may find offensive regardless of age/generation. Then it morphs into a moral issue.
I have two older kids, who, unfortunately, grew up the majority of time away from me, so I never had a chance really to engage in this type of discussion with them. I have some younger kids now, and when the opportunity arises we'll both talk to them about it.