Your dentist needs to learn statistics

Ask your dentist if (s)he can determine when the baby teeth
fall out within a year for anyone? If not, the variation
to determine a person's age by looking at baby teath
would be at least one year.
Then there are at least 1% of the people fall outside
of the 2 years range.

Now there are 10 million girl in China with 16th birthday
in 2008. 1% of 10 million is 100,000. It is well known
certain development type of girl is better at gymnastics.
Case closed!!

I don't know what are the ages of these gymnasts. But
I do know anyone use their gut feeling is showing
their prejudice.