FOr those who didn't see the season finale DO NOT READ unless you liked being spoiled then go right on aheadKya. Katara and Aang had 3 children:
- Kya = oldest, only daughter and only waterbender
- Bumi = 2nd oldest and oldest son, only non-bender
- Tenzin = youngest of the three and only airbender
Amon is a chi-blocker and the fighting style of chi-blockers is based on the same principles as airbending, namely evasion, agility and then hit the crucial points. And he named his son Bumi just after his friend, that's it.
Actually Cali, Amon is a water-bender but probably has some chi-blocking training. The reason he was able to nullify everyones bending was due to blood-bending, which was taught to him and his brother by their father 