Thank (or blame) your parents for more than your eye color or double-jointed elbows. Psychologists pretty much agree that our birth order has a huge influence on our personalities, according to the Child Development Institute.
We consulted experts to find out how your birth order influences various areas of your life, including personality, education, health, relationships, and professional success. Whether you’re the firstborn, a middle child, the youngest, an only child, or a twin, read on for how your place in the family affects you.
Firstborn
Personality
Firstborns are likely to be more Type A, self-disciplined, and even have a higher IQ than younger siblings. The reason? Parents tend to be stricter with them than children who come later. Bonus if you’re female: Turns out all this trailblazing can make you stronger in the real world. Firstborn women end up 13% more ambitious than even firstborn men.
Education
Oldest children must love school. There’s a 16% higher probability of them finishing multiple degrees compared to their siblings, researchers at the University of Essex found. The eldest tend to prefer classes that are based on “mastery” or “self-referenced” goals.
Career
Considering the tendency to pursue higher degrees, it’s no surprise that firstborns turn to careers that require higher education, from medicine to accounting. In fact, they’re used to climbing to the top in business as well: More CEOs are firstborn than any other place in the birth order.
Health
The oldest child tends to be better shielded from germs early on—but that’s not necessarily a good thing, suggests Japanese research. They also tend to have more allergies than younger siblings. The reason: Scientists think those who are exposed to more germs and potential allergens from infancy may have a higher tolerance than their overly protected older siblings.
Relationships
Firstborn children are more likely to find marriage earlier than their siblings. One possible reason? They’re often considered by parents to be the most dutiful of their brood, so they’re seeking mom and dad’s approval once more by getting hitched early. Firstborns also tend to marry those closest in age to themselves. (After all, why marry someone a lot younger who reminds you of your kid sis?)
Middle Child
Personality
Middle kids tend to be more content, more sociable, and better at team sports because of their in-between place in the family. Apparently, they’re so used to playing off the temperaments of and attention given to the oldest and youngest that they often have fewer “acting out” problems growing up.
Education
Middle children don’t do so bad either when it comes to finding their place in the classroom. However, second-borns are better at coursework that emphasizes performance goals (think: standardized tests), where competition can be fierce.
Career
Middle kids—accustomed to handling various personalities at home—tend to prefer jobs that require better interpersonal skills or “group collaboration.” From social work to sales to professional sports, middle kids thrive in the mix.
Health
When compared to the eldest, middle children tend to have a lower body mass index and are less susceptible to type 2 diabetes. The downside? Second-borns are more prone to chronic fatigue syndrome, a complex and somewhat mysterious disease (scientists think it may come from a virus that the oldest and youngest are able to thwart).
Relationships
They tend to be the happiest when it comes to relationships since they live “outside the spotlight” of older and younger siblings. According to Katrin Schumann, author of The Secret Power of Middle Children, middle kids claim to be happier in relationships because there’s no pressure to be perfect (like the eldest) or an expectation of constant attention (like the youngest).
Youngest Child
Personality
When you’re the baby in the family, all that extra attention from siblings and parents shapes your mind, too. The youngest tend to be the most popular among friends, the most agreeable, and also the most empathetic of the brood. The exception: If there’s a large age gap between them and their older sibling(s), they tend to be more like the oldest.
Education
Youngest children may experience the toughest time in school. But they tend to work the hardest to stay ahead—because their parents admit to less supervision. (When “parental monitoring of homework” increases, so does the youngest kid’s grades.)
Career
Used to getting their way as well as receiving lots of attention at home, the “babies” gravitate toward artistic or creative jobs (think publishing, art, and acting).
Health
Youngest children may have fewer allergies and a lower risk of developing diabetes, but they’re actually at the highest risk for health issues related to addictive substances, from drugs to cigarettes to booze. And they tend to have more addictive personalities that ultimately puts their health at risk.
Relationships
The youngest tend to seek relationships that are the most emotionally safe, thanks to the way they learned to approach confrontation, found Brigham Young University researchers. Since they’re used to others taking care of things for them, they treat adult relationships in a similar manner. In contrast to firstborns (who speak their minds freely to resolve issues), youngest children can be tentative about raising an issue.
Only Children
Personality
Only children aren’t used to siblings interrupting them at dinner or jockeying for mom and pop’s attention. They tend to be more independent, less involved in group activities, and less likely to hang with relatives as an adult than those with siblings. (So they can catch up with pals instead?)
Education
Many only children are high achievers with traits similar to those of firstborns.
Career
Again, like firstborns, only children (think: Jack Welch and Alan Greenspan) tend to run the show in business because they’re concerned with maintaining their position at the top at work and in their parents’ minds.
Health
While an only child’s physical health profile doesn’t look different, a lack of siblings can take a toll on their mental health, according to Lauren Sandler, author of One and Only: Why Having an Only Child, and Being One, Is Better Than You Think. Without the buffer of siblings, parents tend to lean on them for support more, especially when they start aging or get sick. The psychological stress of “excessive emotional enmeshment” with parents, said Sandler, is more likely with onlies than those with sibs.
Relationships
When it comes to relationships (as with career, sociability, and education), only children aren’t at a disadvantage. The real issues crop up if their parents’ union unravels. According to Sandler, without the “protective shield” of a sibling to weather the storm of parental upheaval, divorce often puts the singleton at risk of becoming some sort of pseudo-partner to a single parent.
Twins
Personality
Twins share a lifelong extreme closeness that offers pluses and minuses. The good: The bond is deep and strong and they get unparalleled emotional support from one another. The bad: They may deal with identity confusion and problems with independence. Carving out an individual identity may be a struggle that goes as far back as the womb.
Education
Twins share a similar outcome wherein academic achievement just isn’t as important to them as it is to others, according to a Taiwanese study.
Career
To understand where twins excel on the job, think Cameron and Tyler Winklevoss or Mary-Kate and Ashley Olsen—careers where they can work together. The bond is powerful: They don’t feel the need to compete with each other and, in fact, prefer spending time together. Entrepreneurial endeavors are right up their alley.
Health
By the nature of “twinness,” no particular health issues stood out. However, their mother’s well-being is another story. Mothers of twins appear to be healthier than those who have one baby at a time. The reason? Having twins doesn’t necessarily make you live longer, but the sheer stamina and ability to withstand the double-duty pregnancy suggests your mom is of stronger stock.
Relationships
Twins who tend to maintain lifelong closeness are likely to seek out a partner that can match the emotional intensity they experienced with their sib. This “twin yearning” tends to put pressure on partners who can never match up to their beloved’s brother or sister.
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