I have a cousin in her by marriage who is in her 70’s, and who grew up believing that the man her mother was married to, was her real father. He wasn’t. She has no idea who her real father is. I don’t believe she was ever legally adopted by that man. She has never been able to get a birth cetficiate as she doesn’t know where she was born, what name she was born under, or her mother’s maiden name. I advised her to join Ancestry.com and take a DNA test, with the hopes that she’d be connected to others who share the same DNA and common ancestor. She hasn’t done it yet.
That was the way the laws went back then.
We discovered a first cousin that nobody even knew about until 2 years ago. Apparently my uncle (now deceased) impregnated a woman during the war and never knew about the child. The mother was married and ended up selling the baby, as well as 2 of her other kids, for drug money. My newfound cousin is now in her 70s and her kids bought the Ancestry DNA kit for her 2 years ago so she could find her biological family.