User blog comment:GrilledMeatling/Gravity Falls Theory: Who wrote the Books 3, 2, & 1/@comment-25401871-20150217051445/@comment-27020359-20150926115951

Stan's brother is said to have 6 fingers. the books all have a 6 fingered hand on them. Stan would know the most about the books being the brother of the author. I belive that it is in fact stans brother who wrote the books...