My brtoher hit a parked car and that car hit another parked car is he responsible for both cars in California?

If your brother had not hit car #2, would car #2 have hit car #3? If nit then your brother is the proximate cause of all of the damage and responsible for it. If somehow car #2 can be found to share responsibility for hitting car #3 then the answer would change but you have simply indicated that #2 was pushed into #3 by the force of car #1.

A parked car (#2) won't be responsible for causing damage to car #3, so all the damage will be car #1's responsibility.

Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.

Let me ask you something. If you were playing pool, and hit the cue ball into the one ball, which hit the seven ball into the pocket, would you claim credit for sinking the seven, or maintain someone else did it?

Note: For further information, feel free to contact my office for an initial consultation at www.PrometheusLaw.Blogspot.com or by calling 510-910-3198. I have offices in Santa Cruz, Campbell, Redwood City, Oakland, and San Francisco, CA, and I practice Family, Business, Property, and Criminal Defense Law, providing top-tier legal representation at affordable rates for working class clients. While I cannot give legal advice outside of an actual attorney-client relationship, which would entail forming a formal written signed contract, thus allowing me to fully review and analyze the specific facts in your case and conduct the necessary research into the law on point, generally speaking I would answer your question as follows, though this is not legal advice and you should definitely seek an attorney's guidance re: this question of yours:

If your brother caused the accident to car 1, then he may be responsible for damage to car 2 as well, unless car 1 or car 2 are partially responsible for the damage to either car 1 or car 2, e.g., mechanical faults with either car, the way they were parked was unsafe, etc. The specific facts must be reviewed by an attorney.