I would give your parents time to get used to the idea, but you should also stand your ground. You've done nothing wrong and you sound like a responsible adult. Unless you've had a pattern of being irresponsible throughout your adolescence, they should give you the benefit of the doubt and try to support you rather than treating you like a criminal.

I'm pretty lucky I suppose. My wife doesn't love my animals but understands the hobby. My mother loves my snakes and wants me to give her a pair of dumbo rats (I had to tell her I think she has too many other more demanding pets right now herself... 3 dogs and 2 birds is plenty for her until her hip replacement!) My in-laws know about my hobby and at least feign interest even if they don't fully understand why a person would do what I do.

The only person that is a bit negative is my sister. But she just wont go into my snake room and I can respect that. She has horrible dreams about snakes trapping her on top of her refrigerator for some reason... But she never called me weird for doing it. =)

My kids are definitely on-board with both snakes and rats in the house! Even my cats love the other critters in the house...