In my current work I quite frequently find where the husband is not the father of one or more of the children and doesn’t know it. It is more frequent than I ever imagined. Now, most of the time the husband does not know of the abortion. That is very frequent.
Met an acquaintance of a relative a few weeks ago. The guy has an 8 year old daughter by first wife, and they divorced about 4 years ago. Then, he “fell in love” with a gal who was pregnant when he met her, and married her too quickly. He legally adopted the child. Then she divorced him right after he signed the adoption papers. So now has child support for another 16 years, and suspects that was her plan all along.