When you read descriptions of your star sign, it often seems as accurate as if your best friend was describing you.
But sceptics remind us there's no scientific evidence that being a Libra influences your personality and no reason why the position of stars near us should determine how individuals turn out.
We could be overidentifying with the deliberately vague or flattering language of horoscopes, which could describe anyone. And yet... who hasn't glanced at a description of Aquarians and thought, "That's me"?
People feel as strongly about the idea that birth order determines some of your personality.
And while scientific studies have – again – been unable to prove that certain personality traits are more common among youngest or eldest children, it's an area that psychologists do treat as worthy of study.
What's the big deal?
Birth order and personality are, after all, a little less randomly linked than constellations and personality. It's possible and even likely that parents tend to treat children differently according to their birth order.
Eldest children tend to be lumped with a lot of responsibility, as well as lavished with loads of attention. Youngest children may benefit from less anxious parenting from their more seasoned parents, but also less opportunity to bask in parental adoration alone.
Middle children may feel lost in the noise. And some common responses to these situations can emerge eldest or only children who are natural leaders (if a little anxious), socially skilled and peace-loving middles, and charming, somewhat lazy youngest. But before you despair that your efforts won't withstand the power of birth order, don't. None of this is cast in stone.
Many other factors contribute to the development of personality traits, particularly a child's gender (and what expectation parents have of either a boy or a girl), or the number of years' gap between children, not even to mention moving from mom to Gogo and back, blended families, adoptions, death, divorce, and so on, which can all change the constituents of a nuclear family.
Also, "actual and psychological birth order can deviate for several reasons, including illness of one child, size of family, and degree of separation between siblings. Your role in the family based on your age may not be the same as the role you have come to occupy," says Dr Susan Krauss Whitbourne, who is an author and psychology professor at the University of Massachusetts Amherst, in a blog post on birth order.
But if a family blends with another family (after divorce, death or remarriage) after the children are over five or six years old, birth order changes don't seem to make a difference to personality development anymore, as the basic personality traits are thought to be established by then.
"Perceptions and beliefs about birth order may have their effects, in large part, because parents impose their stereotypes onto their children. By assigning these stereotyped birth-order roles, which may interact with gender roles, parents create self-fulfilling prophecies among their brood. You come to feel like the leader if you’re a first-born because you were handed this role early in your life," she adds.
What the research reveals
Famous psychologists Sigmund Freud (an eldest) and Alfred Adler (a middle child) had a serious dispute in the 1920s and 30s about birth order and personality.
Adler said firstborns constantly struggled for success and superiority, and middle children (such as himself!) were healthier, easygoing and rebellious. Freud vehemently disagreed.
These days, psychology has moved towards evolutionary theories of behaviour, where the idea is that siblings compete for parental "resources" (time, affection, food) by developing separate roles or niches (areas of speciality) as strategies to increase the attention they receive. But when recent studies looked at whether birth order for sure yielded certain characteristics, findings have been underwhelming.
In their ebook 50 Great Myths of Popular Psychology authors Lilienfeld, Lynn, Ruscio and Beyerstein say, "In most studies, the relations between birth order and personality has been inconsistent or non-existent. In 1993, Swiss psychologists Cecile Ernst and Jules Angst surveyed over 1 000 studies of birth order and personality. They concluded that birth order is largely unrelated to personality."
A more recent study, say the authors, rated individuals against the "Big Five" personality traits of conscientiousness, agreeableness, neuroticism, openness to experience, and extraversion, and found "no significant relations between birth order and self-reported measures of any of the Big Five traits."
Another study found that eldest children were indeed more intelligent – by just one IQ point. Co-author Professor Rodica Damian said: "The message of this study is that birth order probably should not influence your parenting, because it’s not meaningfully related to your kid’s personality or IQ."
However, first-born children are more ambitious, and they end up earning more than their younger siblings, according to a study by UK researcher Feifei Bu, which found that firstborn girls are likely to become the most highly qualified of all siblings in a family.
If the gap between your first and next child is more than four years, this effect is amplified. It's probably no coincidence that out of the 12 humans who have ever walked on the moon, all 12 were firstborns or only children (and all were men – but that’s the subject for another day...)
Of the first 23 American astronauts in space, 21 were firstborns and the other two were only children.
It's just possible that the bossiest child in the family is more likely to be the eldest, the best people-influencer the youngest, and the best at meditating, the middle child.
But do remember, when you try to "place" your child, that personality is not static but changes over time.
Nobody has to be locked into the rigid role of the eldest child, even into adulthood, if they don't want to. The good news is that parenting plays a role in mediating the harshest effects of birth order predestination – and that everybody who wants one, gets a do-over.
Who is what?
Though there has never been proof of more than a weak correlation between birth order and personality traits, children in these family positions may be more likely to develop the following characteristics: Oldest children can be... leaders, ambitious, perfectionist, responsible, traditional, bossy, conformist, dominating people-pleasers, and they’re also usually well organised.
They may be sensitive to being "dethroned" by younger siblings, and jealous. Only children may feel constantly scrutinised and controlled. Because there's nobody who went before them, these children have to learn independently.
Middle children are often... diplomatic, flexible, open to new ideas, original, easygoing, sociable, and even secretive. Middle children might feel they lack a role that distinguishes them as "special" in the family (unlike the youngest or eldest – this is the much-talked-of "middle child syndrome"), and they may miss that or feel rejected.
Middles and youngest can learn well by imitation or mentoring. Youngest children might become... These guys might be entertaining, risk-taking, rule-breaking, non-traditional, financially irresponsible, pampered, charming and popular – even manipulative.
They might feel permanently on the back foot, less capable than their older siblings, but on the upside, are often able to get others to do things for them. They also might come across as precocious or more sophisticated than their years – thank their older siblings for that.
Share your stories and questions with us via email at email@example.com. Anonymous contributions are welcome.
Don't miss a story!
For a weekly wrap of our latest parenting news and advice sign up to our free Friday Parent24 newsletter.