I personally will not do more than one generation of "inbreeding" when I start up my projects next year. I'm getting a Salmon Pastel boa that is the product of a son to mother breeding and that whole litter turned out just fine so I'd be comfortable with the one time.

IMO breeding 2 to 3 generations in is asking for trouble and at that point isn't so much about the health of the animals but for the money which is not ok.