The real-life Dipper and Mabel Pines! Alex Hirsch has stated that the main characters of Gravity Falls are based on himself and his twin sister, Ariel.
“Mabel is going to be one of the breakout characters of the show. I really owe it to my sister and her many quirks. When we were growing up, my sister was obsessed with the boy band ’N Sync. She even broke her toe jumping up and down during one of their concerts. So, we did a show about a boy band, and of course, I had to get Lance Bass to do the voice of the singer. I had my sister fly down to meet him. She also always wanted to have a pet pig when we were kids, so I gave Mabel a pet pig on the show and she can live vicariously through her. She owes me big!” ~Alex Hirsch
love it! how fun :)