Here's the blurb for Pegged As Curious: Taboo Home Pegging, by Jade Celeste (bolding in original):
"When Nicole stumbles across a novelty sized toy beneath her young man's bed, questions predictably follow. When the young man opens up, his answers lead the woman of the house toward temptation, and into the most taboo experience of her life!"
You can see where this is going, confirmed when you open the preview: it's stepmother and stepson. Apparently the strategy is based on an assumption Amazon will screen the blurb rather than the text. (Leave aside future complaints, if any, from offended readers.)