There's something that has been bothering me for awhile. Is Roku really Ursa's actual Grandfather, or could he be her Great-Grandfather, or even her Great-Great-Grandfather.

Here's why it doesn't make sense:

Now, we know that Sozin didn't have children until later in life and that's possible because he probably had a young wife (maybe even wives). Azulon could have been born not even that long before Sozin died assuming that his mother was significantly younger than Sozin. Now, Azulon probably had Iroh when in his thirties or so, maybe late twenties. Ozai when he was in his thirties or forties. So, Azulon was in his eighties or nineties when he died, so the math works out in that.

With Roku.. He married Ta Min when they were about 28 (since that's when he came back from his Avatar training) She was probably the same age as him. Let's assume they had their first child when they were thirty or so. Fast forward to when Roku died, that child would be about forty, and normally someone has a child by then. So, unless Ursa is over 112-years-old, I can't see how that works.

If Roku had a child late like Sozin, that would make more sense. But the problem with that is, Ta Min is Roku's age, and the normal child-bearing age for women ends at about 50 or so. It is possible that in the Avatarverse, women can have children at an older age, but that's just an assumption; we have no way of knowing that for sure.

So I'm just wondering; do you think it's possible that Ursa's isn't Roku's exact grand-daughter, but great, or great-great-granddaughter?

If any of you are math expects, or have some expertise in human reproduction, maybe you can figure this out for me.

If you can't figure it out scientifically, make up a theory that might make sense.