Birth Order Studies
In the TV show, The Simpsons, 10-year-old Bart is a manipulative, trouble-making little brat, while his younger sister Lisa is an angelic, brainy nerd with mental capacities skyscrapers above Bart's. The two siblings couldn't be more different, as often is the case in real-life families. But unlike in The Simpsons, younger siblings rarely outshine their older brothers and sisters in the intelligence department.
Studies show that the oldest child in a family typically scores higher on IQ tests than the children born after him or her. Each level down in birth order corresponds to diminishing IQ. In other words, the third-born scores lower than the second, the fourth-born lower than the third. Plus, the IQ-factor transfers over to academic aptitude. A 2010 study in New York found that older siblings outscored their younger brothers and sisters in both math and verbal ability.
The differences aren't huge, which should provide some consolation for those third or lower in the family line-up. A 2007 study of 244,000 males aged 18-19 in Norway found that the oldest sibling held just a two-point IQ advantage over the next in line; most other studies have found a three-point differential. A 2.3 difference in IQ apparently translates to about 15 points on the SATs. Unfortunately for later-borns, that small difference in intelligence, according to "some" studies accompanies big differences in achievement, with older kids outpacing younger siblings in virtually every area of endeavor.
Firstborn children represent a disproportionately high percentage of leaders in business, politics, and the arts. Richard Zweigenhaft of Guilford College in Vermont recently analyzed birth order among members of Congress and found that of 121 representatives and senators, 51 were firstborns, 39 were middle children, and 31 were youngest children. Twenty-one of the first 23 NASA astronauts were firstborns. Over half the former presidents of the US were oldest children. Firstborns far outnumber their younger siblings among Nobel Prize winners, famous composers, and eminent personalities, and firstborn CEOs outnumber last-borns almost two to one.
Does this mean, to paraphrase singer Randy Newman, that "younger siblings got no reason to live?" The fact is, although the older siblings may outshine their younger brothers and sisters in the success department, they lag behind in other ways. Studies of older siblings consistently find that they tend to be perfectionists, and perfectionism isn't a delight to live with. Research also shows they're more conscientious, dominant, and organized. But in return, they experience heightened stress reactions, more anxiety, and higher heart rates. And, oldest siblings are far more likely to be the target of mistreatment in abusive families.
In contrast, younger siblings tend to be more extroverted, forgiving, agreeable, and sentimental than their older sibs. Some studies have found that younger siblings function better in social situations, are more independent, and enjoy risk-taking more. There's some evidence that younger siblings are funnier. The latest studies even show that younger siblings perform better in school, grade-wise, in spite of the lower IQ and aptitude. Experts think this may have to do with the fact that their older siblings help them with schoolwork, but on the other hand, they may just try harder.
In other words, older siblings come in handy if you're looking to hire aggressive, success-oriented individuals to drive your company to the top, whereas younger siblings might be better suited keeping the company there once it's arrived. Younger siblings seem to know how to roll with the punches more, enjoy life more, and maybe even make life more enjoyable for others.
The reason for the firstborn edge, most experts agree, comes down to the fact that firstborns enjoy a period of time of undivided parental attention -- until the next sibling comes along. Says Dr. Frank Sulloway, a social researcher at the University of California, Berkeley, "When the second [child] comes along, the oldest still gets half of all that [attention], so younger siblings never have a chance to catch up."
In the animal kingdom, among certain species, it's common for the firstborn to kill the second-born. Perhaps it's inherent programming that drives oldest children to dominate. Scientists generally agree that the differences aren't purely accidental, and while some say nature and others say nurture is to blame, they concur on the fact that oldest children overall do have an advantage. On the other hand, although birth order may matter, there are families where every sibling excels in some way. Just think of the Emanuels, with Rahm and Ari, the two younger brothers, both high-achieving Type A personalities. Perhaps the effects of birth order might be trumped if parents can succeed in lavishing all their children with love, support, constant encouragement, and kindness, while handing each child an equal helping of responsibility and opportunity and holding them to all to the highest standards. As an example, just look at all that PDQ Bach -- the 21st of Johann Sebastian Bach's 20 children -- achieved.