"While other factors, such as age, race, and gender, all play a role in shaping personality, research indicates that the number one factor influencing personality is birth order," explains William Cane, author of The Birth Order Book of Love, who has analyzed the birth order of 6,000 celebrities, historical figures and couples.
Birth order personality
FirstbornBecause firstborns are usually tasked with more responsibility from young to look after their siblings, they typically grow up to be dominant, super-responsible, organized and competitive.
Middle childThe middle child is a people-pleaser. He or she is diplomatic, and it's difficult to get them to take a stand. The middleborn also tends to be a little manipulative.
LastbornLastborns are friendly, creative individuals who love challenging the status quo. They're more adventurous than their siblings and are the risk-taker in the family, although they also tend to be needy at times.
Only childAn only child is used to being in the spotlight within the family, so he or she tends to crave attention. Being an only child also means that he or she is unlikely to know very much about the opposite sex.
TwinsTwins have a strong bond and therefore always think of the other before making a decision. Their thoughtful nature makes them considerate romantic partners.
Birth order compatibilityWhen it comes to birth order compatibility, studies suggest that opposites attract and the best birth-order mixes have the least of what Cane refers to as rank conflict: "Two firstborns, for example, have the same rank and would be expected to fight over who's the leader," says Cane. "Similarly two lastborns could be expected to experience conflict over who's to be considered the baby of the relationship."
So which marriage combinations work best? Dr. Kevin Leman, author of The Birth Order Connection, shares his findings: