Are Police allowed to contact my parents if they are investigating me on drug dealing?

Basically I'm 20 years old and tonight have been told by my parents that Kent police are investigating me on drug dealing. This is not the problem as the police are just doing their jobs, but what I think is really wrong is that they have gone to my parents before I knew anything about it. I can say now that I don't deal drug but I do occasionally smoke hash. What I really what to know is, are the police allowed to do that as they have completely ruined my relationship between my Mum and Dad as they now don't trust me. That and they don't have any evidence to back up these allegations, not enough to get my parents involved... Thanks