I thought they were a part of the raccoon family.
Genetic studies suggest that the Giant Panda is a true bear and part of the bear "family" but diverged a long time ago. There is no evidence of it being related to raccoons. Yes, I'm grabbing this from Wikipedia but the sited scientific articles can also be found on their page.
The Red Panda on the other hand is its own family but is closer to raccoons, skunks, etc.