Perhaps as a witicism it could be suggested that he comes from the same planet as Gonzo, and are decended or evolved from the same creature. Sorry just a joke, the question I'd like to ask is how does it matter. There are probably a number of similar planets to his home world just as Kasshyk is similar to Endor which just had shorter inhabitants but similar dwellings. Perhaps Degobah is similar to his original home. Actually I'd imagine likely if he was happy to make a home for himself to go into hiding.