[Gupta:] We're back with HOUSE CALL. You know, with the presidential election looming, Elizabeth Cohen takes a closer look at candidates according to birth. Does being a first born ensure a smoother path to the presidency?
[Cohen:] What do Hillary Clinton, Barack Obama, George W. Bush and Gerald Ford have in common? They're all the eldest children in their families.
[Kevin Leman, Psychologist:] The first born's rule.
[Cohen:] Literally, they do. In the past 70 years, more than half of U.S. presidents have been first borns.
[Leman:] They tend to dominate. They tend to control. They tend to be opinionated.
[Cohen:] Psychologist Kevin Leman wrote the book on birth order. He points out that four of the past six presidents have been eldest children. George W. Bush, Bill Clinton, Jimmy Carter, and Gerald Ford. George H.W. Bush was second of five and Ronald Reagan was the baby of the family. Even among people who try to become president, first borns rule at least this season. Eight of the 11 major candidates who started the 2008 race are eldest or only children. John McCain is not. He's a middle child. Leman says leadership comes naturally to first borns. After all, they had to take care of younger siblings. And a new study from Brigham Young University says first borns with one sibling get more time with mom and dad. About 20 minutes more quality time per day with dad and 25 more minutes with mom. There are many who say this birth order stuff is squishy science, that the research is flawed and paints families with too broad a brush.
[Joe Rodgers, Psychologist, University Of Oklahoma:] There are many first borns who are natural leaders, but there's nothing about being first born that automatically leads to leadership.
[Gupta:] Others beg to differ. They point to studies showing first borns are more likely to be CEOs, surgeons, MBAs. While birth order certainly can't predict the presidential race, history shows it's a factor. Elizabeth Cohen, CNN, Atlanta. Thanks, Elizabeth. Stay with CNN for unparalleled political coverage and check out the most viewed political blog on the web. It's the political ticker at CNN.compolitics. Also, make sure to tune in next weekend for a very special HOUSE CALL. We're going to be providing weight loss inspiration and practical tips so you can be ready for spring for summer. Remember, this is place for all your answers to your medical questions. Thanks for watching. I'm Dr. Sanjay Gupta. Stay tuned now for more news on CNN. TO ORDER A VIDEO OF THIS TRANSCRIPT, PLEASE CALL 800-CNN-NEWS OR USE OUR SECURE ONLINE ORDER FORM LOCATED AT www.voxantshop.com