Scientists and parents have believed birth order shapes personality since the late 1800s. Psychological giants like Francis Galton, Alfred Adler and, more recently, Frank Sulloway suggested that firstborn children received special treatment and had greater power than their later-born siblings. As a mom of boys born one minute apart, I've often wondered whether the “firstborn effect” applied to twins.
“The idea that birth order affects personality has profoundly penetrated the parental consciousness,” says Brent Roberts, a psychology professor at the University of Illinois at Urbana-Champaign. Parents across the globe say their oldest takes the lead, the middle child plays the role of mediator and the baby grabs attention at every opportunity.
