You're only half of parents' age when you all are same age, What happens to Feb 29 babies?

Question

I don't understand

February 29 babies aren't happy.

for title of post

You’re only half of your parents’ age once. And when you are, it was the same age as when they had you.

1. How can I prove this mathematically? This doesn't feel intuitive.

2. Feb 29 is a leap year day. So what?

Answer 1

The ratio of your age to your mother's age starts out as 0:1 when you are born. As time passes, that ratio increases, limiting toward 1:1. There is only one moment in time when the ratio is 1:2.

When that happens you are $T$ days old and your mother is $2T$ days old. But subtract $T$ from both numbers to go back in time to when you were born, and your mother was $2T-T=T$ days old. So at that moment, you are the same age as she was when you were born.

It's a joke that if you were born on Feb 29, you only get to age one year every four actual years. For these people, with that understanding, the ratio of their age to their mother's age still starts out at 0:1. But it increases over time, approaching 1:4. It never reaches 1:2.