Identical Issues
You and your twin have the same favorite hobby, which is embarrassing when it's something like extreme knitting or taxidermy.
You both want to decorate your bedrooms in identical themes, like neon-lit, 80s video game arcades or disco ball-covered dens.
You and your twin have the same sarcastic responses to every situation, which gets old after the first 100 times you both say it at the same time.