Are You Born Great or Made Great?

Oct. 22, 2009 — -- How could Michael Jordan, born with once-in-a-generation athletic abilities, soar as one of basketball's greatest players of all time ... only to whiff his chance at a career in Major League Baseball?

Or why has William Shatner with his talent in the performing arts been acting successfully for over four decades in hits like Star Trekand "Boston Legal," but failed to launch a singing career?

In their new book "SuperFreakonomics," authors Steven Levitt and Stephen Dubner propose some answers.

"The fact is, if you look at anybody in the world who's really, really good at anything, the odds are that they were not so great at that when they were a little kid," Dubner said. "This whole idea of raw talent and genius are vastly overrated."

Born to be a great soccer player or a pianist? Not so, says Dubner. Sometimes something as simple as the month you were born can help make it possible for you to succeed.

Watch this story and more "SuperFreakonomics" on "20/20" Friday at 10 p.m. ET

"It's a bizarre, but very pronounced pattern, that if you look at, let's say, world class soccer teams, a lot of the guys on those teams were born in just a few months of the year -- turns out January, February and March. And very few of them are born, like, October, November, December," he said.

Dubner said this is not an astrological anomaly. Aquarians are not better soccer players than Sagittarians. Instead, the pattern exists because the cut-off age for youth soccer is Jan. 1 and being the oldest kid on your junior soccer team -- if only by a few months -- can actually determine your chance of becoming a professional soccer player.

"The older kids are bigger. They're a little more mature. They're a little faster," he said. "And then the coaches are looking for the best players. They select them and they keep doing this over and over, year after year."

Coaches give positive feedback to the bigger kids, reinforcing their success.

"What's remarkable is that this effect, this relative age effect, lasts all the way up into the professional ranks," Dubner said. "That's what's really so astounding about it."