Gruncle Stan
So Gruncle Stan is actually Dipper an Mable's fathers uncle . . . I only say this because his full name is Stanford Pines and they are Dipper and Mable Pines . . . That means Stan has to have a brother and that brother has to have a son leading to Dipper and Mable. (Unless of course a girl decides they want to pass on their name which is VERY unlikely due to we can assume the show uses common logic) Now I'm not saying the supposed Stanford's twin brother is real but there is a higher chance of him now. 1. The car saying the Stanely mobile. 2. Stanford has to have a brother. 3. Twins run in the family usually. 4. In Stan's memories the boy who covered his face with the book has the family hair 5. The spare room in the mystery shack 6. And finally The glasses and the fez are both on the Bill Cipher Wheel He may be real or he may not :T I dunno I just wanted to put this out there