I’ll darken a different part.
One of her findings is that there is no single all- encompassing reason why observant Jews cease to be so. It can be the coolness of their own observant parents to religion, or the difficulty they have with teachers in school. It can come from their own sense of the religion’s simply ‘not working’ for them. There are many , many reasons. And the author is honest enough to say that she has no formula for any specific case.