Legal Question in Family Law in California

I assume you meant to ask at what age a child can choose whom to live with. The answer is 18. Before that it is up to the agreement of the parents, or in the absence of agreement, then it is up to the court to determine what is in the best interests of the child. Once a child is mature and intelligent enough to form a reasoned opinion, most judges will take the child's wishes into account as one piece of evidence in making the decision, and the more mature, intelligent and objective the child is, the more weight the child's preference will carry, but it is never up to the child.