Quoting "Steemit Terms of Service":

Steemit is not targeted towards, nor intended for use by, anyone under the age of 13. You must be at least 13 years of age to access or use Steemit. If you are between 13 and 18 years of age (or the age of legal majority where you reside), you may only access or use Steemit under the supervision of a parent or legal guardian who agrees to be bound by these Terms.