My parents are firmly in the "wait until you're married" camp. I'm... well, not.
As far as I was concerned, they didn't have to know anything... until Mr. aephi alum and I decided to move in together. Realizing that my folks would notice that our addresses were suddenly the same, I broke the news gently to my mom. She took it surprisingly well, asking only if we were using protection.
My dad is another story. He could write the book on living in denial. We've been married nearly 5 years; I think he thinks I'm still a virgin.
