They just showed the episode of when Schneider meets his 19 year old son that he never knew that he had.
That makes two of us because I don't remember this at all!
I remember thinking it was so dirty when I watched it the first time as a child. Back then teen sex was not discussed.
I'm a month younger than Mackenzie and certainly wasn't having sex in high school. It wasn't discussed like it is now, but from what I gather from class reunions and Facebook memories, there were a lot more people doing it than I ever imagined.