I asked the same question and got multiple replies that many folks on here had bred visual x visual without any problems (including albino and pied).


*And now for the obligatory genetics rant .... *


... And really, as BG alludes to in the boas, there is no real reason why visual x visual should have more problems than het x het or visual x het. At the end of the day, either the snake is homozygous for the desired trait (morph) or it isn't, and it's either homozygous for the defect gene, or it isn't.

Using the albino boas as an example, if the defective recessive gene (eyelessness) is linked to the gene for the desired recessive trait (albinism), it's entirely possible to get eyeless albinos no matter what the pairing. If the defective trait (eyelessness) is actually a pleiotropic effect of the albino gene (ie, the albino gene ALSO causes eyelessness), then you really are JUST as likely to get it no matter what the pairing.

However, in albino boas I would guess it's a linkage thing simply because the rumor persists about not breeding albino x albino. Reason being, the more closely related the parents, the more likely each one is going to carry the defective gene, and the more outcrossing in the bloodline, the more likely you were able separate the two and get an animal that carries the albino gene but not the eyeless gene. (Unless the albinism gene really does cause eyelessness and the rumor was just invented by breeders to get people to continue buying albino boas ...! )

So really, I suspect the real problem was that the original albino also happened to carry a gene for eyelessness that was fairly closely linked to the albino gene, but vigilant outcrossing can separate the two -- and obviously has in a lot of animals.

It seems like it would be more important to avoid breeding closely related animals in bloodlines with known problems than to avoid visual x visual ... Then again, you also risk propagating a defective recessive gene if you don't know about it. So, then there's that.