Firstborn kids are bossy. Youngest siblings are brats. Stop us if you've heard all of this before. Researchers have been fascinated by the effects of birth order for decades, but what does Science have to say about these personality "types" popular culture has thrust upon us?
The idea that birth order affects our personality dates back to the early 1900s with psychologist Alfred Adler, who believed that second-born children were generally more well-adjusted than firstborn children, who have no choice but to feel "dethroned" by their younger siblings.
Then, in 1996, psychology professor Frank Sulloway, PhD, suggested that a person's expression of the "Big Five" personality traits (extraversion, agreeableness, neuroticism, conscientiousness, and openness to experience) had a lot to do with their birth order. According to Dr. Sulloway's work, older-born or firstborn children are more responsible and assertive, while later-born or youngest children are more imaginative and affectionate.
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Subsequent research aligned with Dr. Sulloway's claims. And lo, countless pop-psychology personality quizzes were born.
But since then, several studies have found little to no connection between someone's personality and their birth order position. A 1999 study suggested that factors like gender, race, and class (which Dr. Sulloway claimed had less of an impact on personality than birth order) were actually more influential to a person's social attitude. And then, a study published in 2015 that looked at data from thousands of people across the U.S., the U.K., and Germany found that birth order had no effect on the Big Five.
Research in this area is still ongoing, so it's impossible to say with 100% certainty how birth order does or doesn't affect your personality. For now, you might not be able to blame your chronic lateness on when you were born, but the good news is that you don't have to accept that "bossy" or "bratty" label, either.