Jess20 merits repreating:
"I don't think it's particularly unusual or abnormal for young people to behave like that for so many reasons. For a start they are experiencing enormous cognitive changes, their hormones are surging and their emotions are all over the place. You seem concerned about two things, firstly, your hint that it's unpleasant sexist behaviour is, to me, the most worrying aspect - I assume he isn't learning that at home. Adolescent boys are influenced by their peer groups and can be quite obnoxious as they start to learn to negotiate the complexities of male/female relationships and there's a huge problem with this sort of behaviour in universities at the moment. Hopefully he'll mature into something more civilised if he has good role models at home. The second thing seems to be his 'rudeness'. I'd suggest that as the more experienced adult you try and regulate your responses to his behaviour and stop yourself getting wound up and emotional about it. Perhaps, without too much pressure, you might even encourage him to chat about the things that are making him react in the way he is. Listen to what he has to say and try and understand his point of view. Many young adults of this age are seriously anxious about genuine issues like, for example, climate change, they feel angry and powerless and see the attitudes of some of the older generation, politicians etc as dangerously complaisant and stupid. As others have said, he's probably as keen to visit you as you are to have him - he an almost grown-up but too immature to be left home alone."