So he didn't know who their dad is? So he is not related to the kids?

The white hair , snake guy ? He's just a babysitter from a babysitter company. The Mc is the uncle of the triplets (on his sister's side)

I’m pretty sure it’s said in the first chapter that the baby’s are his sisters kids and that the run away because it was too much for her with the babies..

I thought he was lying
I truly thought it was his kids but he lied to others kind of stuff

I think he said in chapter 1 that they’re his sister’s kiddos ╮(￣▽￣)╭