The Stranger in my Genes by Bill Griffeth (Boston, Mass.: NEHGS, 2016) is a great read. I got the book and in two days I was done. It's not long (180 pp.) but a real page turner. Ostensibly it's about genealogy, but that's not true. It's about dysfunctional families. It is true that none of what happens in the book would have happened had it not been for genealogy. It is because of genealogy that Bill, the author, takes a DNA test which sets in motion the contents of the book. For those of us involved with genealogy who have already taken a DNA test (I've taken two), we can breathe a sigh of relief that this did not happen to us. In fact, the NEHGS weekly newsletter recently had a poll about DNA testing and I could truthfully report that my results were boring. They completely backed up what I knew on paper. But Bill, gets the surprise of his life to find out his father is not his real father. And consequentially half his genealogy is wrong.
I also watch Genealogy Roadshow on PBS and I note that 70-80% of the queries on that show revolve around the "I didn't know my parent and/or grandparent." The researchers then use genealogical tools to fill in the person's knowledge of this very close family member. Again this is not genealogy, but dysfunctional families. These people need a genealogist less than a psychologist to help them work out their identity questions. But with genealogy becoming the number one hobby in the U.S., this is what genealogy has become. (I would define genealogy as proving relationships in the distant past). The key there is distant past. You didn't know Grandpa who was in WWII, then that's a communication problem between Grandpa, your parent, and you.
I must say though that I called my mother up after finishing the book and told her, in no uncertain language, that if my father was not my real father, she could keep that secret to her grave. I didn't need to know. But, of course, I already know how I came to be in this world. There's no family secret about that.