Change up in the question: Did your parents know you were drinking in college? I like to think my parents didn't know but I also know they aren't stupid about what goes on even though nether of them attended college.
I started drinking in highschool and my mom and I came to the conclusion it was best if I just told her when I did. It allowed her to not worry and I always had a ride home or place to crash and could talk about it with her. We figured I would do it one way or another, why not have her in the loop.