Do we know anything about Obito's parents?
The Naruto Wikia article on Obito Uchiha states:


  Obito grew up not knowing who his parents were, leaving him alone and forced to fend for himself. This sad upbringing led Obito to dream of one day becoming the Hokage so that the people of the village would acknowledge his existence.


So I think no, he didn't have any parents, siblings or friends, until he met Rin and Kakashi. That is why he was obsessed with the Eye of the Moon plan. On second thought, I think Obito was rejected even by the other Uchiha, so he was totally alone.