I havent had this problem, but when my brother was small he bit my dad, so dad bit him back (just hard enough to get the message that it hurts) and he never bit again. My SIL has the same problem with her eldest shes nearly 2, but she bites her if she gets mad or is in trouble, SIL doesnt reallly do anything about it which i guess is why she still bites - she has also bitten chunks out of my DD's windowsill - not that SIL will admit it was her but Em wasnt crawling when i first noticed them.