Board Thread:General Discussion/@comment-28431168-20160617130858/@comment-26233737-20170105222211

Capitano Nox wrote: ARE you sure? I thought he said something like that... Well, um, technically, nah.

Sans never said that.

Anyways, there isn't much concrete evidence specifically stating that Gaster is Sans and Papyrus's father. They most likely have some realationsip, but not necessarily  a father-son one. Still, I like the idea of Gaster being their dad.