To answer your question, Mabel & Dipper were both born in 1999. Now I know they're 12 but maybe they're gonna turn 13 somewhere in the series during the summer. My friend was born in 1999 on 12/21/12. LOL the day of the end of world. LOL.
Hi. I'm Julie and I live in Tokyo Japan. I Read your profile and saw that your in seventh grade and still like Gravity Falls. Don't Worry because I'm in seventh grae and in my school there is a group called Gravity Fallower, but there is only 3 members and I'm one of them. Well nice talking to you!