entry number 17 dark darker yet darker the darkness keeps growing shadows deeper

When Gaster worked for Asgore, he probably would have connections of some sort with Undyne, which might be the reason Sans/Paps have authority, as being connected to the Captian of the Royal Gaurd. So when the 'Gaster Disaster' happned, Sans and Papyrus would have moved to Snowdin, where nobody would have known them, as they just moved there, and the fact that they just, 'asserted themselves', could also be explained by being Gaster's sons. Also, as said by the shopkeeper rabbit lady in Snowdin, Sans and Papyrus just appeared one day, which I believe is because they were in the Capital, living with Gaster when he was the royal scientisc (ie: pre-core accident Gaster).

Sans and Papyrus also speak in a diffrent font that is unique to the characters, as it is their typeface, and forms the name for the character, as does Dr. Also, Sans does seems to have connections of some kind with the G, not to mention his liberal usage of Gaster Blasters.

Gaster seems to be the only skeleton, or skeleton-esque entity in Undertale.

I personally support the theory that Sans and Paps are Gaster's sons for a few reasons.

Entry number 17 dark darker yet darker the darkness keeps growing shadows deeper