Is this possible with jQuery? If so, how would it look?

I have a simple form where I collect some basic user information. (name, birthday, e-mail).

If the user fills in the form and they are between the ages of 13-17, I need another 2 text fields to be required (for a parent's signature & email). If they are over 18, the field isn't required. It would be really amazing if those parent fields wouldn't be displayed unless their age was under 18.

I have no clue how to do it. Really appreciate any help!

Thanks!