I think I figured it out everybody.

So spoilers, like y'all havent watched already lol

>!Try this on for size. Coop did the video for Vault 4 with the Hawthornes.They were studying effects of radiation on humans.eventually we see them create the Gulpers but that probably wasnt the ONLY creation.Vault 4 overseer says taking in the surfies is a vault tradition going back generations. When the Bombs fell Coop goes to Vault 4 and is an experiment leaving him half ghoul. It could also be where the Ghoul drug comes from and why Coop knows so much and had access to it for so long.!<

What do you all think?