Why do many people assume that you are still a virgin if you are living with your parents for years after graduating from college?

Its an independence thing. People will assume that if you're not "confident" enough to move out on your own, get a job, and live your own life in your own house; Then what makes you confident enough to date, let alone have sex with someone. In my opinion, I don't really think it matters if you are a virgin or not. But for everyone else it's not only the confidence thing, but also a joke. Most of the time it's not that serious. While people may question your independence if you don't move out some time after completing your education/finding a job, I've never heard of people assuming you're sexually inexperienced. However, living with your parents may somewhat hinder your relationship prospects. What's important is if both you and your family are happy with the current arrangment. Many cultures have several generations that live together and many adult children take care of aging or ill parents. If you feel that your life is being hampered, or if you're not helping your parents financially, then you should start looking into finding affordable housing.