_A Numerate Life_, John Allen Paulos. I've enjoyed his classic books (_Innumeracy_) but this grumpy memoir-skeptical memoir didn't have much IMO. It did have something though, an observation that almost no one is entirely normal.
Imagine that 90% of people are 'normal' on some dimension. Imagine that there are lots of mostly independent dimensions: height, IQ, sexual orientation, kink, family history, travel... if there are 10 such, then under 35% of people are normal on all dimensions. If 20 such, 12%. Up to you to decide how many ways you could characterize people, or how many of them to treat as normal.
_Port of Shadows_: years later, Glen Cook returns to the Black Company series, with an interquel, set after the first book. It was a gripping read, and possible inconsistencies were lampshaded within the text...
See the DW comments at https://mindstalk.dreamwidth.org/500270.html#comments