I agree with both of the posts above me, you have to tell your parents all they want is what's best for you.
You don't know how they'll react, they could be totally cool with it or they may say you should wait until your a little more mature, either way so long as you haven't "done anything" there is nothing you should fear by telling them.
You have nothing to hide and by hiding your relationship you send your parents the signal that something is wrong with it or the boy, you shouldn't have to hide love.
If your parents do not want you to start dating/date this guy it may be heartbreaking at first but in the end everything will be alright and work out.
"There Is No Need To Rush. If Something Is Meant To Be: It Will Happen In The Right Time, With The Right Person, And For The Best Reason."