How Much Inbreeding is Acceptable?

[sho220]

First question - what are the right terms for the parents of a litter? Sire/dam? I'll just use that terminology - hope that's okay....

I was looking at some ads on KS, and I saw someone selling a pair of BPs (1.1, obviously, being a pair), and they had different dams but the same sire.
The way the ad was written and the way the person was selling the snakes, it was apparent that the intention of selling them together was for them to be bred.

Is that generally accepted?

How much inbreeding is deemed 'okay' for snakes? Are deformities/health issues common in snakes inbred to a certain extent? (Shortened lifespan, even)? How closely related do snakes need to be inbred before such problems are seen?

I know some (most, maybe?) snakes come with paperwork, but how far back in the line does paperwork usually go? I know with dogs, you can go back tons of generations. There are some pedigrees with German shepherds (just using an example) that can be traced all the way back directly to Horand von Grafrath - the first registered German shepherd. I don't expect snakes' bloodlines to be quite that inclusive, but how many generations are included on paperwork? Just the sire and dam? Or are there more?

Any insight would be appreciated!

Inbreeding is generally frowned upon except in West Virginia...