Board Thread:Questions and Answers/@comment-27491885-20151228162741/@comment-28925112-20170113040216

Murderman21 wrote: I'm not sure just where I found this, but I've heard before that the two are fraternal twins, or brothers given birth to (or created) at the same time. Papyrus takes on the older brother roles of cleaning, cooking, and work. Sans is super lazy and adopts the role of little brother. I personally like this idea. Maybe Sans was just born a minute or two before Papyrus, which still makes him older.