Board Thread:General Discussion/@comment-27524978-20160210030742/@comment-27805791-20160215220901

Not sure anything I have to say is definitive proof that he's wrong, but I'll make my contribution anyway.

To start, MatPat's theory does not explain:

Sans' love of ketchup, knack for puns, outright manipultion of spacetime, knowledge of (but no ability to partake in) past resets, nihilistic worldview, and his time machine (seeing as the only one Ness had exposure to was kept in some collection (heard from an outside source- may not be completely true)).

The theory outright goes against:

Sans' being a monster. In the lore of Undertale, it is stated that human souls persist upon death. This in no way implies or hints toward their continued existance as a skeleton. Going further on that, it seems even less likely that a dead human would become a ''monster. Sans has only 1hp despite Ness' ability to accumulate hundreds, ''has the ability to use attacks Ness couldn't have imagined (Gaster blasters, manipulation of player's soul, bone waves), and is recognizable by the player in a photo, despite Ness being completely alien to Frisk's cannonical life.

So what explains all these allusions to Earthbound/Mother??

Simple- Toby Fox really, really likes the series. He went so far as to make a fangame/ROM hack, and it seems a major source of inspiration to him in general. So it's most likely he's paying homage to Earthbound than to say Sans is Ness, if you ask me.