I bit my nails growing up, still do at times though I don't bite them till they bleed and hurt anymore. Anyways, you'll sometimes find yourself biting before you even realize you're doing it and if you were like me, you feel the need to finish biting that particular nail but the key is to stop once you realize you're biting. It will be hard because you'll know that the job isn't finished so to speak. Do that along with stopping consciously biting and you can stop and then, instead of spending time biting you can spend idle time cleaning dirt out from under your new nails. Seriously just stop biting them and if you catch yourself doing it without realizing stop now, go get clippers and clip the "unfinished" bits but all it takes is an effort not to bite them.
Maybe you need to learn how to wipe your ...? Oh wait, you have a baby right? Anyways, I think it is disgusting.
Well, I have noticed, in my new favorite habit (thanks OP! -- what a great thread!), that nail biting is particularly wonderful a few hours after, say, eating a big plate of BBQ ribs.
Also, don't be afraid to try other people's nails! You would be surprised how different diets can affect the taste and texture. Leery of asking your friends and family? No problem - just ask a stranger at a bus stop for a sample.