Yes, there should be jokes about race, about countries, about religion, children, adults, boys, girls, lesbians, straight, gay, transgender, programmers, computer-illiterates, politicians and laymen or any other way to slice and dice humans into groups. Joking about things is one of the fundamental freedoms we value - it's one way to deal with preconceptions we all have about us and other people. Good jokes take your prejudices and turn them around, turning them into an unexpected lesson.
Now, not all of those jokes fit into any environment. And neither should fun be derived from putting someone else down, like racist or sexist jokes do. And then, there's always the question of "what's funny?" So the best way to handle things is: The more people listen to you, the more you err at the side of caution.
Sure, and my somewhat cheap response misses the subtleties, see my response to JohnnieCache - at a conference with women in attendance and slides/etc. with an obvious 'aren't these women fucking sexy we geeks don't get much of that do we? Haw haw' edge to them, are such 'jokes' really making light of sexism or not? I think very much the latter.
The problem I have with your cheap response is that it actually clouds the issue. The question you and me should be asking is "why would it be appropriate to have sexist (or rather offending) jokes in any moderately public setting?" You're getting side-tracked by your parent who intentionally(?) uses "political correctness" and a move to a global statement as a way to stifle the discussion about why the jokes in question are certainly inappropriate for a public audience. It's not a question of "which jokes are we allowed to tell?" but rather a question of "are we allowed to offend participants on a conference/meetup/...?"
Now, not all of those jokes fit into any environment. And neither should fun be derived from putting someone else down, like racist or sexist jokes do. And then, there's always the question of "what's funny?" So the best way to handle things is: The more people listen to you, the more you err at the side of caution.