What Birth Order Can Predict About Your Health

Some aspects of who we are are unavoidable, we’re simply born into them. For example, our eye color and hair color, or even certain genetic disorders. However, there are other aspects of ourselves that we develop as we grow, like our sense of humor or general outlook on the world.

Or at least that’s what we always thought.

Scientists are now saying that we are all predisposed to fall into certain personality type. The determining factor for what characteristics we do or do not have? Our birth order.

We’ve all heard the cliches of the lonely, misunderstood middle child or the attention-seeking youngest, but are those true? Are these labels simply stereotypes or proven characteristics that we inherit?

Naturally, there are experts who disagree over the issue. But the overwhelming consensus is that birth order can determine more than just who you are, it can also determine health issues that you may face in your life.

First Child

No surprise here, first born children are natural leaders. In fact, most of our American presidents have been first borns! Oldest children also tend to be more ambitious than their younger siblings, especially if they’re older females, and they have a distinctively more Type A personality. They’re less likely to take risks but have been proven to be a few IQ points higher than their little brothers and sisters.

What’s more, first born children are often considered the “favorites” in their family. This can be a good and a bad thing, for multiple reasons.

From a personality standpoint, this parental attention causes pressure on the oldest child; they develop self-critical tendencies and often have higher expectations placed on them.

In a health sense, first children tend to be more carefully shielded from germs than younger children. This often causes oldest kids to have more allergies and lower immune systems.

First-borns are also at high risk for high blood pressure. Brand new research has come out to suggest that this may begin in the womb. It’s known that the mother’s placenta, which provides the fetus with nutrients, may not work as well in her first pregnancy, and this may have adverse effects on the fetus and its development.

The pressure and driven nature of first borns also increases their stress and blood pressure; this means first-borns are at a greater risk for cardiovascular disease later in life.

Middle Child

Now being a “middle child” can mean you’re literally in the middle of three kids or that you’re kid four out of seven. All it means is that you’re not the oldest and you’re not the youngest. So, needless to say, these health problems and personality traits apply to a good many of us!

Middle children are typically the mediators and peacemakers of the bunch. They’re good listeners, negotiators and they aim to please. They are usually more secretive and often feel isolated, replaceable, or lost in their own family and will seek company outside the home. This makes them very loyal friends. Interestingly, the more kids you have in the middle, the less strong these characteristics become.

According to some new and preliminary research, they are most at risk for chronic fatigue syndrome. This is a mysterious syndrome which scientists are still working to get to the bottom of, but they currently believe it stems from a virus which oldest and youngest children are able to thwart.

Good news for middle kids, they tend to have a lower body mass index and are less susceptible to type 2 diabetes than their siblings. They’re also more sociable, often more athletic, and feel less pressure from their families; because of this, they tend to be more easy going than their older siblings.

Youngest Child

Ah, the baby of the bunch. Besides getting coddled or picked on by your older brothers and sisters, there are some distinct traits and health issues associated with your young status.

Youngest children tend to have big, playful personalities; scientists believe this is because they struggle to get attention over all their older siblings. This makes them prone to creative work, like art or acting. Although they may struggle in school more than their older siblings, they are the most popular and likable of their family by far; they’re certainly confident and charming.

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. Their addictive personalities tend to come from their attention-grabbing tendencies.

Only Child

Being the only child can be a blessing or a curse. You may be jealous of the relationship your friends have with their siblings, or love how close you are with your parents because you’re their only priority. Either way, you have your own characteristics and health risks, too.

Like first borns, only children tend to be independent, driven, and academically successful people. However, like the youngest children, they tend to be more confident and more prone to taking risks than others. Only children hate to be critiqued, as they are Type A perfectionists, but they’re creative and imaginative, too.

You could say they’re a mix of the oldest and youngest in a family, in the best way.

Unfortunately, only children are at the greatest risk for obesity. The theory is that an overprotective caretaker of an only child may show love with food, which starts a bad habit at a young age. There’s also a negative mental component involved with having no siblings.

Lauren Sandler, author of One and Only: Why Having an Only Child, and Being One, Is Better Than You Think, claims that because there is no buffer of other children, parents tend to lean on their one child more for support. This is especially true 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 siblings.


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.

Contrary to some siblings, studies show twins don’t feel the need to compete with each other. They generally love to be together and find joint entrepreneurial endeavors are right up their alley.

No particular health issues stood out just because twins are twins. However, their mother’s strength is another matter. Although this is not a blanket idea, the sheer stamina and ability to withstand the double-duty pregnancy suggests your mom is of stronger stock.


As we mentioned, not all experts agree with these findings. A recent study, which was recently published in the Proceedings of the National Academy of Sciences, examined more than 20,000 adults from Great Britain, Germany, and the United States through self-reported surveys.

The psychologists behind the research ultimately concluded that the “big five” traits (conscientiousness, extroversion, emotional stability, agreeableness, and openness to experience) are not impacted by birth order.

This is, of course, one study in a sea of hundreds.

What is your experience with birth order, personality traits, and health? Were these findings accurate for you? Share your experiences as a first-born, middle child, youngest child, only child, or twin in the comments section below.