My father died in 2000, and his wife (my step-mother) died this year, she has no descendents(children). There is property left that they jointly owned. My father's brother and my step-mother's brother have taken control of the estate. Don't I have a right to my father's estate? To his and his wife's jointly owned property?

Yes, file a notice with the court that you are the son of the property owner,

249. At any time before the hearing any person interested in the
Property may answer the petition and deny any of the matters
Contained therein. The court shall hear the proofs offered by the
Petitioner and by any person contesting and shall make a decree
Conformable to the proofs. The decree shall be prima facie evidence
Of the facts determined thereby, and shall be conclusive in favor of
Anyone acting thereon in good faith without notice of any conflicting
Interest.





Link is to California Probate Codes:
http://www.leginfo.ca.gov/cgi-bin/ca...ebody=&hits=20

You should get a California probate attorney for advice,

In most areas where I am from, after your faither dies, any "joint" property goes to the living spouse. So in a few years if that spouse dies only her relitives not his would have any claim.