Novel by Mameve Medwed
"Host Family" can mean two things. Either the local recipients of non-local youngsters, usually from overseas; or types of species frequently preyed on by parasites. This book, then, is about the history of a long-standing host family and its present breakdown. Parasites in many forms play an important part of it.
It's a good idea which could have been executed wonderfully. Unfortunately, this book isn't. I find both characters and plot severely lacking in depth and credibility. Take the parade of exchange students, for instance. All the ones from Africa and Asia are annoying demanding, and cook too spicy food. The students from Europe, on the other hand, are all beautiful and actively seductive. To give a more concrete example of the author's lack of understanding for non-Americans: At a prize-giving ceremony (for long service as a host family, of course), two Englishmen shout "here, here" (no, not "hear, hear") during the appraisal speech, like "bored MPs during those sessions of Parliament you sometimes see screened on C-SPAN". For the record, I don't think any Briton not Parliament would ever shout that - except as an expression of utter sarcasm.
Then there are the people in the process of breaking up, the host family. It's all told from the perspective of Daisy Lewis, and so we get the perspective of a slighted wife, quite heavily. Her husband seems not only utterly ridiculous, but also unbelievable. As part of his midlife crisis, he starts learning French, which from then on he spouts at every occasion. Henry, who now calls himself Henri, also insists on wearing a jaunty beret. He picks up their French exchange student at the airport, and within minutes, so it seems, she has fallen for him. We are never explained why - maybe it's his heavily accented French?
The funny thing is that author of this book teaches fiction writing. I guess it proves the old adage: Those who can't do, teach.