Chances are you haven't pushed your chinchilla to the point where has bitten. Chinchillas in general do not bite and if they do, except when provoked, it is considered a serious behavioral problem. However I know some animals have calmer personalities than others. My first chin was very territorial and aggressive and in order to make any progress with training him I had to push him because he was so opposed to being handled and acted like a wild animal when I got him. The conditioning methods I used worked well though and at the end he acted way more domesticated and would not bite under normal conditions. In fact he even seemed to do okay when we had to syringe feed at the end although he was obviously stressed.
My second chinchilla is very hyper and skittish around any kind of commotion. He'll bark at noises when my mom cleans the house sometimes. He doesn't like to be held still to the point where it was very difficult to handle him until I conditioned him by actually restraining him in short sessions. Now he is just fine and very pleasant to handle but it took getting bit a couple of times to get him to that point initially. He'll often kack at the two year old baby when she gets too close because she'll pat him in a closely supervised but not too gentle way. I allow this so he knows to move out of reach of her and not become aggressive towards her. Oddly enough he becoming is more apt to let her come up to him the more I have him downstairs and perhaps will one day just take it. I don't expect him to but who knows? No two animals are going to be the same but I've found that sometimes you must systematically and slowly introduce animals to things they don't accept before they'll accept them.
As far as genetics goes TOVs can in theory be bred together but a kit cannot inherit two TOV genes and survive. You can imagine the two sex cells coming together and combining their genes inside the ova. The ova develops into an embryo. If there are two TOV genes from both sides the embryo will die somewhere along the development because the combination is lethal and causes its systems to malfunction. There is some debate on where exactly that point (maybe only after a few cell divisions) is and whether or not this is bad for the mother so it is best practice to not breed two TOV chins together. Same goes for the white gene. It is said the gene carries a "lethal factor" and you see this with different genes in different animals as well.
