His introspective memoir tries to challenge the conventional wisdom about his upbringing, explores his marriages and airs a little dirty laundry — but says relatively little about politics.

California’s governor has been touted as the Democrats’ best shot in 2028. But first he’ll need to convince voters that he’s not just a slick establishment politician.

Mr. Newsom, the California governor and a potential presidential candidate, writes that the privileged caricature of his background is mistaken.