Board Thread:General Discussion/@comment-30306971-20161023220253/@comment-33883848-20190923153101

Toby Fox hinted TWICE that Gaster is Sans and Papyrus's BROTHER father.

-One of his famous tweets indicate that Papyrus had another relative and the third one is censored.However,"a father"named "Gaster"doesn't fit with the censored part instead "another brother named Gaster"does.

-In Toby's "important info"tumblr post,Sans mention that it's "rude to talk about people who are listening"followed by "Not everyone is as though as my brother".Considering Papyrus lack of omniscience and that the line "it's rude to talk people who are listening"is exlusievely related to Gaster in the game,the brother is likely Gaster.