Sometimes people questioned whether or not Tenzin was the Avatars son. It was certainly not a question of faithfulness between his mother and father, but of personality. He was, in a lot of ways, the complete opposite of his father. Where his father was lighthearted, energetic, and only took things seriously when they needed to be taken seriously. Tenzin on the other hand was ALWAYS serious (not to mention he inherited his mother's famous temper.), carrying the weight of an entire civilization that his father never forced on him. He believed that if he was not perfect he would somehow "shame" the air benders of the past and pushed himself to the brink to meet standards that his father never set.
While Aang eventually helped him work past those fears they came back in full force years later when he had children of his own. He was worried that he would push his insecurity's as a boy onto them and not be able to teach them the "spirit" of an air bender. But as the years passed and he eased into teaching Jinora, Ikki, and Meelo the ways of the air nomads Tenzin found it almost eerie how much his children had in common with a grandfather they would never truly know. While they each had a pacifistic personality and a love of nature they each had qualities that were purely Aang.
Jinora had inherited his determination and thirst for knowledge. She always wanted to learn something new and was never deterred when she failed at something. And for some reason she seemed to have also gotten his romantic heart, (which Tenzin did not appreciate one bit) always hanging on every word their grandmother told them of how romantic her husband had been. Granted, most little girls are like that. But it seemed Jinora more so than others.
Ikki had his positive attitude. Never out of things to say or do, she always looked at things from a "sunny side up" perspective. She also seemed to love animals the most out of the three. (Even if sometimes they did not love her.)
Meelo did not listen, had a short attention span, fell asleep during lessons, and was even a bit lazy. But he was perhaps the one with the rawest talent. Even if he was not as skilled as his sisters, he quickly picked up on new forms and thought outside the box to create moves that were…interesting.
Everyday day that passed and they grew a bit wiser and stronger Tenzin could not help but see a bit of Aang in them. And each one of those days he told them that they could be safe in the knowledge that they were making him….and their grandfather very proud.