If a boy cut his long curly hair as a toddler and then his hair stayed short and nappy for thirteen years is it possible for his hair to grow long and curly again?

Yes. As long as he takes care of it, it will grow out the way it was.

Mine did that. when i was a toddler i had ringlet curls that were really cute but i wanted a bob so the hairdresser had to cut them off. mum was upset that the curls were gone but the hairdresser said that around puberty they would come back. it happened. now i have WILD curly hair.