Your aunt sees that you are 38 years old, single, living with your Dad, in a superhero themed bedroom. Regardless of what people here tell you, that definitely gives the appearance that you've never grown up. Having a home with a comic room is something most people can appreciate (whether they understand it or not). Being almost 40 with a superhero bedroom at your Dad's house isn't the same thing. It's no different than an adult decorating a bedroom in a sports theme or cars, or a similar interest. Tell your aunt that she took your space if she keeps nagging you. Don't bring any dates home either if you like them. People have changed their view on comics in general, but not to that extent. Get your own place with a spare room, fix up that room to the max, and spend all your time in there. Get a nice comforter set, some curtains, and a couple of non-superhero pictures for your bedroom.