Did you talk sex with your parents when you were 13 years old? Mom..dad, can i have some condoms? I sure as hell was not going to discuss sex with my mother, let alone tell her i was taking the pill. I asked her one day why didn't she ever talk sex with me when i was a teen.... her answer was that she thought they taught us about it in school.
If parents have no inkling of what their children are up to, what makes you think they will fess up when something bad happens if they can deal with the problem themselves?