I got a corn snake yesterday, he's a captive bred and he's ~4 feet.
When I bought him I asked to know how old he was and the lady told me he was about 1 year old.

Can that be right? 1 year old and be 4 feet?

I've read adults reach 3-5 feet.
Is 1 year old considered an 'adult'?

I'm kind of new to this so I thought I'd ask.
I know that captive bred snakes aren't over fed so I imagine their grow rate is based on how much they eat plus genetics, correct?

Thanks in advance.