I only thought I could stop watching cartoons because of how my cousin once said she doesn't watch cartoons. I was 15 and she was 14. I had some relatives over, and another one of my cousins was looking through the channels for something to watch, and she found what happened to be a cartoon that she'd watch. The first cousin I mentioned just harshly stated "I DON'T watch cartoons". Mind you, she started acting all adult-like when she was about 10.
The following summer, we happened to work at the same job. The Mortal Kombat movie had just come out, I saw it, and so did a couple of these guys there. We were discussing it for a bit, and she just says that's kids stuff.
Even around that time, I'd still watch cartoons, but the non-kid-oriented ones like The Simpsons, Beavis and Butt-head, and South Park. Though eventually, I went back to watching other kinds of cartoons. I started watching Digimon near the end of my final year of college. After that, I'd move on to X-Men Evolution, TMNT 2K3, Transformers Animated, The Spectacular Spider-Man, Wolverine and the X-Men, and now I'm watching Transformers Prime and G.I. Joe: Renegades. Someone should have told my cousin that trying too hard to act grown-up is a sign of immaturity.
If someone doesn't like to watch cartoons, or doesn't share my others interests, it's cool with me. What's NOT cool with me is if they'd dis me and/or turn their nose up at me for liking what I like.