Board Thread:General Discussion/@comment-26811160-20151220053636/@comment-8161155-20151220212438

1.  Stan and Ford are early sixties. I think the important thing a lot of people are missing is that Stan and Ford didn't necessarily not see each other for only a decade. Stan said it was "over ten years", so it is entirely possible that they are in their sixties (and seeing as Stan sees himself as "pushing seventy", it's certain beyond reasonable doubt that they are.)

2. I think it's much better for our childhoods if we assume that the baby was not Dipper and Mabel's grandfather. Assuming the baby would have been born in 1969, and Dipper and Mabel in 1999, that leaves thirty years for the baby and his child to have the twins. Thirty divided by two is... fifteen.

No one said Stan and Ford don't have an older brother.