Cal. Prob. Code § 21622

If, at the time of the execution of all of decedent’s testamentary instruments effective at the time of decedent’s death, the decedent failed to provide for a living child solely because the decedent believed the child to be dead or was unaware of the birth of the child, the child shall receive a share in the estate equal in value to that which the child would have received if the decedent had died without having executed any testamentary instruments.