Well I'm a woman and I learned coding by myself in exactly the way you describe. I personally don't think it has anything to do with gender. I didn't find many study partners within my major that I could relate to so I just studied by myself. This continued to lay the groundwork for a continuing self-education after college. I don't think this is so weird, but certainly it's nice whenever you have a supportive group around yourself. I wouldn't discourage anyone from seeking that out but I can't say I needed it either. If anything, I came to prefer the independence of working on my own much more.