some banks allow you to have a visa debit card at the age of 13/14 dependant on country etc, so if you are old enough to have a bank account and old enough to wire transfer funds from it. then there is no issue with some services. localbitcoins.com for instance will have no issues with this. but read the terms of service of bitstamp and kraken

bitstamp
By opening an account to use the Service ("Account"), You expressly represent and warrant:

    1. You have accepted these Terms; and
    2. You are at least 18 years of age and have the full capacity to accept these Terms and enter into a transaction involving Bitcoins.

kraken
You further represent and warrant that you: (a) are of legal age to form a binding contract (at least 18 years old in the U.S.);