Its definitely not genetic in spiders. in mammals Defects are hereditary or based on diet is Rome & Greece had a decree against deformed babys , It is cruel but its history of most of the anceint world. Regardless Inbreeding spiders generally leads in smaller size Id imagine , since runts survive much more than in wild. Anothereason why Lasiodora aren't as big as original Wc specimens. I beilive sizes were over-aggerated also too , I doubt A LP could ever reach 11".
11" prob not.. but better then the 13-15" some people claimed from lo and stirmis back in the day
Most species of T's in captivity have come from a small number of w/c specimens, and therefore wind up being related to each other and inbred. That's the nature of the hobby. It's far too expensive, and often legally difficult (if not impossible), to keep introducing new blood from the wild, when so many species come from remote tropical regions. Yes, more slings from a sac survive in captivity than the wild, but remember too, that vast majority of exotic T's (at least in the US) die as virgins. When a runt reproduces there's another set of genes in the mix, and it may just mean a smaller number of eggs, not necessarily smaller spiders as adults.
Especially in SA, where it is illegal to import arachnids, no one has ever had success in obtaining a permit for importing arachnids here in SA (at least that I know of).