The beneficiaries of the life insurance policy aren't dependent on family relationships. Your father could have named anyone as his beneficiary, whether or not they are family. If he didn't name his beneficiary, the life insurance contract would have a default provision. One can't be sure to know what the default was without seeing the life insurance contract, but it would likely have either been his estate or his spouse.
You don't indicate whether your father had a will, but you seem to have some expectation that you should inherit. If he didn't have a will, it is likely that your mother (his wife) is entitled to most if not all of his estate. If he had children that weren't the children of his wife, they may have a claim if the estate exceeds a certain amount. This Avvo legal guide helps to explain how an estate may be divided if a California resident doesn't have a will.
Even if he did have a will, if he lived in California then at least part of his estate is likely community property and would belong to his wife. If you have questions about where you fit in inheriting his estate you'll need to contact a local probate attorney because there are a number of facts that attorney would need to have to advise you properly.