it varies from person to person, situation to situation, and the why. it's not always stupid, it's not always smart.
in some instances it's perfectly fine to inform them just to inform them. in others, you're just asking for a negative experience.
i personally wanted to tell my mother, i wanted to know what she thought about it. sort of like getting a secret off your chest (but not in a guilty way).
i know her well, she's a very supportive and kind person. the worst that would happen is she might ask why. i was just sitting with her, chatting, and just spoke about it. she wasn't upset or even confused, apparently she knew i was the kind of person who enjoyed such things, so it made sense to her. after that, i wanted her to watch an episode with me and she did. it was one of the my most enjoyable experiences. my father watched it with us, just because, and he obviously doesn't really care about any of it.
some people don't have parents like that. some will kick you out of their house for just mentioning you might be biloveual. some will be disappointed, others won't give a stuff what you do at all.
if you know what your parents are going to say, and you know it's going to be bad, you are just asking for whatever comes at you. that is when it is downright stupid.
there is nothing wrong with informing them though. good parents like to be involved with their kids and their interests.
