Genetic defects?

Looking Lottie and Dash today, i realised that they seem to be developing to look like very different species, strange because well... they're the same species.
Lottie is turning into an axolotl looking creature with long thin limbs that she always has spread out. But Dash , despite being larger than Lottie, has normal front legs, but his back legs are short and thick and always tucked right in to his tail.
Water conditions as a factor are eliminated at the moment, i posted all the details in a previous post but for the last couple of weeks they have been fridged (on its lowest power setting, with a towel around them so they don't get too cold) and the water has been charged once at least, sometimes twice, a day, always dechlorinated and aged.

So i guess my question is, is it possible for axolotls to have genetic defects that would cause something like this?
Also if a breeder was inexperienced for instance, the eggs were an unexpected accident, or the parents were juveniles, could this have an effect on any batches of babies?

Thank you.

Not sure, we'd need pictures to see if one really is deformed or injured + being able to see exactly what kind of defect it is.

Also for your other questions: the breeder has nothing to do with the genetics, it's possible they did something wrong before you brought them but it's just as likely you did something wrong.
I don't know what could happen to the eggs, as far as my knowledge goes they are pretty protected. As far as I know the only side effects of the parents being juvies is smaller clutches and potentially dangerous for the female. I don't know anything about birth defects being caused by young parents.

Oh i know it could have been something we've done as well, i was just wondering how far a breeder has an effect on things like that as i know it can have a massive impact in lots of other species that are bred as pets. If it was just the one leg i would be more inclined to think it was something in his environment, but as it is both and everything else seems to be developing fine, as does his tank mate, it just seems less likely. Plus i suppose I'd rather it not be something we've done wrong, although i know it is entirely possible.

It's probably genetic. But like I said, pictures would help.

If it is what i think it is the stumpy one may start to develop fluid retention. Bloat right out. I had 4 with thisgenetic issue and i noticed that underdeveloped stumpy limbs were something in common