Do muscles grow naturally during puberty?

I'm 16 years old and idk i seem to be growing muscles on my body, i even have an 8 pack like i don't even work out of do sports lol how is this possible?
Answers

Josie

Yes. Though exercise will encourage them.

Anon

Muscle tone depends a lot on genetics. But yes testosterone has a lot to do with muscle tone as well.

Eddy

This is not good at all! You must see a doctor immediately!!! You could be at risk for ALS!