“And it all goes to show just how strange Robert A. Heinlein was.
From a devoutly religious upbringing, we have a teenager who threw off religious belief and embraced atheism at a time when this would have been profoundly shocking. From the 1920s we have an enthusiastic practitioner of free love and “companionate” (read: open) marriage—in an age when cohabiting without a marriage license was a felony. And from an early age, we have an enthusiastic naturist, during a period when it was considered wicked and shameful. Somehow a radical free-thinker emerged from a bright but poor background (he was working from age 10, only able to read and study on the streetcar to and from school)—and promptly bent his every effort towards the goal of getting into Annapolis as a naval officer cadet!”
3.5 out of 5
http://www.tor.com/blogs/2010/08/through-a-backward-telescope-heinleins-context
