Amos, look at it this way:

Suppose when you were 15 Kendall was 30. You were 50% his age.
So 15 years later, you're 30 and Kendall is 45. Now you're 67% his age
When he's 90, you'd be 75, or 83% of his age.

In short, you're catching up. Eventually you should pass him.

This is mathematics, so it's gotta be true.