How to search for potential family that my grandfather denied
Back in the 1990s, someone reached out to my paternal grandfather (now deceased) in search of their biological father. He was enraged and denied having any children outside his marriage (with my grandmother).
I was a young child at the time but overheard a conversation about it, which is the only reason I am aware of the incident. My own father basically chalked it up to a nasty prank.
But I've reflected on this several times throughout my adulthood, and I believe it is very possible that my grandfather could have had a child outside his marriage. My grandfather (and most of our family) are US Southerners, born and raised and still live in the South to this day. But my grandfather joined the Navy during WWII when he was a teenager, and he spent some time in California, the South Pacific, and Alaska. So I feel there were definitely opportunities there, and being so far removed geographically from the local community, no one would ever know.
Additionally, pretty much everyone on my dad's side of the family are all very self-righteous, very hypocritical, and very "religious" people who never accept responsibility for their wrong-doings. They always deny, deny, deny. So I don't trust my grandfather's reaction to the person who reached out to him. And I also can't ask my dad about it, because I already know with complete certainty that he will just get defensive and be offended.
Anyway, I don't know who the person who reached out to my grandfather was, I don't know if it was a prank, and I don't know if it was a legitimate attempt to find their father. I also don't have much money to invest in searching for "maybe-but-maybe-not" long-lost family members. But I do have a desire to make some kind of effort to try. Does anyone have any recommendations on starting points or smart strategies?