The Match by Harlan Corbin (2022) Grand Central Publishing

Wilde, who was found surviving in the woods as a child, now grown and still living off the grid, sent in a saliva sample to see if he could track down the parents who abandoned him.  Now, he's getting hits from this.  He's also getting pangs of jealousy over the wife of his best friend, even though the friend has been dead for years.  But what is real, and what is only in his imagination?  He tracks the man who is supposed to be his father, only the man and his family disappear shortly thereafter.  He tracks a cousin, only to find he's not really his cousin, but this one became a celebrity, and he too has disappeared.