Yup. Just the fact that everyone wears them without any thought in the matter. As soon as I was old enough to think and decide for myself, I nope'd out of them. Do you actively say "yes, I want to wear jeans"? or is it something you grew up with and so you never thought about changing? As a side note: I enjoy seeing different styles of fashion (like in Harajuku) but it seems most people just go with the t-shirt+jeans look. Which is fine, but it's a bit boring to see it day in and day out.
Actually, I chose not to wear jeans for a long time. Like, 10 years. Then one day I found a pair that fit really well and that was that. As for boring, I can understand that. I am also fine with that. It's unusual to see me in something other than jeans and a white t-shirt. That's more of a habit though. I used to work long hours at a restaurant and then have class all day, so instead of doing laundry I just bought packages of white t-shirts from the discount places downtown, near school (I do laundry more regularly now). Edit: until 2012 I pretty much wore business clothes during the day but . . . I haven't exactly been doing business since then.