Johnny Eck, a "half-man" born with no legs, grew into a proficient hand-walker.

In 1940, a Dutch goat was born without front legs and learned to walk upright. So did Faith, a two-legged dog in Oklahoma.

Minnesota conjoined twins Abigail and Brittany Hensel live a successful life with separate heads on a single body. With each controlling her own arm, they've mastered driving, swimming, playing piano and even shuffling cards.

Such are the "freaks" that University of Iowa psychologist and professor Mark Blumberg examines in his latest book, "Freaks of Nature." He uses these oddities of nature to explore the development and evolution of the body, brain and behavior. By focusing on physical abnormalities, how they happen and how creatures adjust to them, he portrays his belief that the nature vs. nurture is moot-they are inseparable and equally important to development.

"To me, the nature-nurture debate is a dead end," Blumberg, who teaches behavioral and cognitive neuroscience in the UI College of Liberal Arts and Sciences, said in a statement from the university. "Asking whether something is more nature or more nurture is like asking whether a hurricane is more wind or rain. It's both -- always both."

To those scientific purists, Blumberg enumerates that genes alone cannot explain all aspects of development. Humans, like all mammals, have both X and Y chromosomes, for generating both males and females. Many other species, like alligators and turtles, don't have separate chromosomes-the temperature that the eggs are incubated at determines the sex of the animal. When it comes to gender, temperature and chromosomes are interchangeable, according to the statement.

"Such examples of interchangeability help reveal the inadequacy of thinking in terms of nature and nurture," Blumberg said. "In the end it is the system that matters, and complex systems cannot be neatly divided into nature and nurture."

What about the nature vs. nurture debate? Is it one or the other or both? AHN wants to know what you think about the age-old debate. Email us at newstalk@allheadlinenews.com