Fun fact: Twenty-one of the first 23 American astronauts were firstborn children. Not so fun fact: Being first out may also increase your risk for diabetes and hypertension, according to new research from the University of Auckland in New Zealand. Researchers monitored the blood pressure and glucose absorption rates of 85 children. Insulin sensitivity—a major risk factor for diabetes—dropped 21% among firstborns compared to later-borns, the study found. The “oldests” also suffered from higher blood pressure, which could eventually develop into hypertension, according to the researchers. Why firstborns? Studies show that a mother’s placenta, which provides a developing fetus with nutrients, may not work quite as well during first pregnancies, explains study author Wayne Cutfield, MBChB, a professor of pediatric endocrinology at the University of Auckland. But you’re not doomed if you’re the oldest—Cutfield says proven risk factors like poor diet or cigarette smoking also play major roles. And on a more positive note, the study also found that firstborns tend to be taller and slimmer than their siblings. So what else can your birth order say about you? We’ve got the scoop: Firstborn? Your IQ rocks. That’s according to research published in the journal Science. A massive study of roughly 250,000 kids found that, on average, intelligence declined 1 to 2% from firstborns to seconds, seconds to thirds, and so on. The Norwegian study authors hypothesize that mentoring younger siblings and helping them with tasks provides the IQ boost. Your friends come from the same group. A recent Harvard University study found that firstborns are more likely to be friends with other firstborns, second-borns friends with second-borns, etc. Why? Certain personality traits—like dominance among firstborns, or individuality among youngests—may dictate the type of people you gravitate toward. Oldests achieve, youngests rebel. Or so says research from Richard Zweigenhaft, PhD, a professor of social psychology at Guilford College. In one study, Zweigenhaft concluded that firstborns are 30% more likely to be elected to prominent political positions. Multiple studies have also shown that CEOs are at least 10% more likely to be firstborns. On the other hand, a separate Zweigenhaft study published in Political Psychology notes that middle- and later-borns are more likely to participate in protest demonstrations. Why? Parents give their undivided attention to firstborns, while later-arriving siblings have to share time and resources. Those attention disparities may increase the likelihood that oldests want to please, while youngests lash out, Zweigenhaft’s research shows. More from Prevention: Your Dreams, Decoded Questions? Comments? Contact Prevention’s News Team.
