Board Thread:General Discussion/@comment-5808856-20150312001702/@comment-26072045-20150710022256

Aardvarkbanana911 wrote: OnlyOnTuesdays88 wrote: Aardvarkbanana911 wrote: Dragonian King wrote:

Aardvarkbanana911 wrote: Stanford is Grunkle Stan. Stanley Pines is Grandpa Stan. The Grunkle Stan we know is Stanley, and the Author is Stanford. Stanford, the Author, is their great-uncle, and Stanley is their grandfather.

Neither are their grandfather. This was confirmed in the preview. I still hope they're keeping that a secret and it turns out not to be the case but for now they're both great uncles unless we learn otherwise. So... they have another brother who's the grandpa of Dipper and Mabel? Extremely stupid and unnecessary but it seems likely atm.