15.
Grayson and Ethan Dolan contacted BuzzFeed News by email, about where they get their inspiration from and why they think their Vines are so popular.
They wrote: "We get the inspiration for the ideas from real life situations and from the usual questions that many strangers ask us about what it's like to be a twin. We believe that these Vines became popular because the ideas behind them are things that everybody wonders about twins."