The conventional wisdom in every family seems to be that first-born children are overprotected, hyper-organized eggheads, youngest kids are rebellious layabouts, and middle kids are starved for attention. But an October 2015 study suggests that idea is a total myth: Your personality has absolutely nothing to do with when you were born.
German researchers used data collected from around 20,000 people from three large national surveys in the United States, Great Britain, and Germany. Using such a big group of people, they were able to crunch the numbers to figure out how a variety of traits differed when it came to birth order.
The results, published in the Proceedings of the National Academy of Sciences, deflate the myth that first-borns are Type A and youngest kids are Type B. First-born children perform better on intelligence tests, and also believe they are smarter than later-born people do, (It might be because of helicopter parents, who are making them nearsighted, too.) but when it comes to the "big five" traits that make up your personality — extraversion, emotional stability, agreeableness, conscientiousness, and imagination — birth order has no effect.
So why do siblings seem to behave so differently? Researcher Julia Rohrer told Time that it might just be a self-fulfilling prophecy. Older kids may think they have to be control freaks, so they behave that way, and then their siblings follow suit, each behaving the way society expects them to. So let your hair down, first-borns. Middle children, you be you. And youngest kids, wear a tie every so often. There's nothing stopping you.