Quote Originally Posted by BRC View Post

It's a huge leap of logic, but one can reasonably follow from the other. Tarrlok was a teen when his brother ran away. The Avatar Wiki puts him at age 37. That's at least two decades for Noatak's hatred of his father to turn into a hatred of all bending.
I suppose so, but it sure would have been nice to get at least a glimpse of his thought process.