It is not necessary for a teenager to be 18 years of age before he can manage a business successfully though it depends on the nature and size of the business. I started managing a small scale business before the age of 18 and I did wonderfully well.I just believe that if they are more than the age of 18, they are capable of managing out the business perfectly ,because they will do this out of passion and not for the sole purpose of making money, doing it with passion is the most effective way for success.