Legal Question in Wills and Trusts in California

It depends on whether or not your father adopted the children or included them in his estate planning documents. More information is needed before anyone can answer your question. For instance: Is your mother still alive? Were your parents married together at the time of you father's death? Did they own property together?

Depending on the circumstances, it is also possible they are legally presumed to be his children, in which case they would share in the estate to the same extant as biological children. you should consult an attorney with the specifics.

Mr. Dorfman is correct. There is an automatic and supposedly irrebuttable presumption that any children your mother had while married to your father and cohabitating with him are his legal children. Although it is supposed to be irrebuttable (meaning you can't even present contrary evidence) the courts have come up with a variety of exceptions. If none of the exceptions apply, however, and your father did not leave a will or trust specifically omitting those children, they would be entitled to a share of his estate.