This brings to mind the childhood of John Stuart Mill:

- Learned Greek starting age three.

- Was studying Plato at age six.

- Studied Latin starting at age eight.

And more: https://en.wikipedia.org/wiki/John_Stuart_Mill#Biography

I guess it helps that he had Jeremy Bentham hanging around his house from an early age.

Learning three languages at an early age is completely unremarkable for millions of people around the world. It's just notable which ones his were.

And imagine what he could have done if he had done something useful at such a young age!