Her father was a college professor in upstate New York. Her mother started a school. But in the 1970s, Nina Planck's parents bought 60 acres in Virginia and, with their three children, started a new life -- as farmers.

The Plancks made a living selling produce at roadside stands and farmer's markets. Their children were forced to eat real food. They grew up healthy and strong. But in her teens, Nina became a vegan. She had been 5'5" and...