Joe McGinniss Jr. wasn’t looking to get into the family business.

The 37-year-old resident of DC’s Cleveland Park is the son of Joe McGinniss, who topped bestseller lists at age 26 with The Selling of the President, about the 1968 Nixon campaign; he went on to write such bestsellers as Fatal Vision.

Although McGinniss Jr. says his father warned him against being a writer, his debut novel, The Delivery Man, is out this month.

After working for San Francisco mayor Willie Brown, McGinniss—who grew up outside of Philadelphia and studied political science at Swarthmore—had doubts about a life in public service, finding the political world “filled with BS.” Unsure about a new career, he started a master’s in public policy at American University.

“Every semester, I’d tell my wife, ‘I gotta get out,’ ” he says. “So I started writing short stories in the mornings before class.”

After graduation, he took odd jobs—from academic counseling at AU to working in dog daycare—but kept writing. Now he writes full-time.

The Delivery Man, set in Las Vegas, follows a twentysomething who gets wrapped up in an underage-prostitution ring. The book grew out of McGinniss’s fascination with Sin City and the hardscrabble lives of those living off the Strip.

“Something about Vegas struck a chord,” he says. “It’s full of contradictions and dangers and the most basic aspiration: prosperity by any means.”

McGinniss, now a father himself—his wife, Jeanine, who works at Fannie Mae, gave birth to a son eight months ago—says that last Christmas he showed his dad a partial draft of his manuscript for the first time.

“My father went on the porch and sat there in the cold,” McGinniss says. “He came back 30 minutes later and didn’t say anything. Then he gave me a thumbs-up and this tight-lipped-grin. I’ll never forget that moment.”

Rachel Deahl has written for Slate and the Boston Globe Magazine.