Are adult children entitled to father's estate if his will left everything to second wife?

In general, if a father's will explicitly leaves everything to his second wife, adult children may not be entitled to the estate unless they can prove that the will is invalid or if there are state laws that provide for a portion of the estate to children, such as in cases of omitted heirs. Some jurisdictions have laws that protect the rights of children to a certain percentage of the estate, regardless of the will's provisions. It's important for the adult children to consult with a probate attorney to understand their rights and options based on the specific circumstances and laws in their jurisdiction.