My twin brother was much more popular than I was in high school. I was one of the nerds working hard to get into a good school. I never heard anything about the parties, drugs, sex, etc. going on until my senior year. My own brother rarely talked to me about what was going on.

Don't talk about it to outsiders, it's really nothing new, just easier to not accidentally slip that you were at a party someone else wasn't invited to.