yeah mako and bolin said the firebender killed their parents they said nothing of having another brother there with them? and if so amon would be way older than they were i dont think they're family but they can be connected by the firebender attacking their families

Maybe Amon is their father?

how could he be their father if they're benders and he isn't?

They never said that it's genetic. The first benders learned from flying bison, dragons, giant moles, and whatever the Water Tribe learned from.

I think bending is more a spiritual thing than genetic. Also Katara's father wasn't a bender. So even if it was genetic, he'd only have to be with a bender. Also, Tenzin's wife has 3 (possibly 4 in the future) air bender children, but she's not a bender.

The waterbenders learned from the Moon. Could you imagine learning anything from this mother fucker? Also, Katara's mom was not a bender as well.

Oops. Just found out that she was lying. Derp.

If you watch the Southern Raiders episode you see that in the last raid they are looking for the last waterbender in the Southern Tribe. Kaya knew that this was Katara and took her place so that Katara would not be killed.

Yeah, I just read that. xD So yeah, even more reason to think that Amon could be their father? Though it wouldn't make sense that he would be on his father's farm. He was young when his parents were killed, and Mako and Bolin's parents were killed in Republic City most likely, seeing how they were mugged.