Jack Cashill's Who Wrote Dreams of My Father raises a question that may not be that hard to answer. When the satirical novel Primary Colors by "anonymous" came out with its unflattering look at the Clinton campaign apparatus, quite a few media outlets went in hot pursuit of the author. Political reporter Joe Klein was quickly identified as the culprit by those who compare writing samples as a profession, such as professor Dan Foster. In addition to being hired to track down the author of Primary Colors, Foster also worked on the Unabomber case and other criminal prosecutions. Foster maintains that writing styles are surprisingly distinctive. Such things as a preference for dashes, a fondness for parentheses or an over reliance on "however", "for example" or "nevertheless" are a writer's DNA.
When it comes to matters of theme and language, many of us who consume novels for a pastime can attest that it can be hard for a writer to disguise his voice even when trying to do so. A great many well known novelists have published under more than one name. According to the delightful a.k.a. Dean Koontz has published under 11 pseudonyms, Harlan Ellison, 25. Stephen King has written under the names Richard Bachman, and John Swithen. The reasons for doing so are many. The late John D. MacDonald was such a prolific writer that in the 1950s he'd have multiple stories in the same issue of a magazine running under different pen names. The publishers of those magazines wanted to use his work, but didn't want to seem that like he was taking over their title. Then there is protecting the author's brand. When an established author wishes to try another genre, the publisher may not wish to let down fans who have come to have certain expectations of "their author", so a work in a new genre is best published under a pen name. Then there is simple reader prejudice. Women readers don't buy romance novels written by men while sci-fi has historically been dominated by writers with male sounding names. .
One of my favorite novelists, Bernard Cornwell, writes historic action novels. It turns out that soon after he published his first two swashbuckling Richard Sharpe novel set in the Napoleonic wars he also published several novels under a woman's name in the bodice ripping historic romance genre. The gig was up as soon as the romance novel got to the first action scene. Barbara Cartland never wrote about the rule that every fan of Richard Sharpe knows by heart: The point of a sword always beats the edge in single combat.