I never had a talk from my parents. My doctor did give me sort of a "talk" when I was 12 or so, but that was more of a safe sex spiel about condoms, birth control, and STDs rather than sex itself.

As for kids, I think it depends on the child. Ideally, I don't think there even would be a formal "talk," but instead having an open, uncensored environment where the child would feel free to initiate any questions or conversation on the topic as they're raised (instead of the common and ridiculous US strategy of actively trying to shield children from any type of sexual information). Though I think it would be a good idea to emphasize safe sex at a certain point.