What does this quote mean O Romeo wherefore art thou Romeo?

This famous quote means "O Romeo, why are you Romeo?" In Shakespeare's play Romeo and Juliet, Juliet is lamenting the fact that Romeo is a Montague, and she is a Capulet. The two families are sworn enemies, and their love is forbidden. Juliet is asking why Romeo had to be born into the Montague family, because it makes their love impossible.