Craigslist(the usual, Accidental litter). They got the babies' parents from a local who breeds rats for food and pets. They said that they fed them a homemade mixture of Oxbow and several other things. When we met to pick up the rats she seemed like a nice person. I did notice that she didn't ask me any questions at all.Where did these boys come from? What did the seller tell you about them? How much do you trust the person you got them from?
At this point, it's probably doesn't change anything if they're actually 4 or 5 weeks old. I don't think there are a lot of breeders on this forum. A breeding facebook group, the r/RATS subreddit, or the RatsRatsRats discord might be good resources if you're looking to sleuth this out.