I know this has come up before...but isn't it kind of weird that there is no homozygous form of Spider? How is this possible, genetically speaking? The mother and father each give one copy of a gene to the child. If both parents were spiders (had one copy of the spider gene) then isn't there a 25% chance the offspring should inherit both copies? Is it the case that the homozygous form is lethal/ends up in slugs or is the gene located in such a way that two copies aren't possible??

If two copies were possible, then theoretically these homozygous spiders should produce ALL spider offspring when bread to a normal, and I know of no such spider existing.

JonV