Does Birth Order Really Determine Personality?

Does whether you’re the oldest or youngest child in your family really have an affect on your personality?

The idea that birth order might affect personality goes way back to the year 1874, when Francis Galton noticed that most of the 180 prominent scientists he looked at were firstborns. This was the first in a long line of scientific and pseudoscientific publications on the birth-order effect.

In 2003, researchers polled people about what they knew about birth order, and found the majority of respondents thought those born earlier had a greater chance of a prestigious career than those born later, and that those different career opportunities had to do with their specific birth-order-related character traits. The “facts” about birth order are so well-known, that in 2018 a Dutch satirical news website posted a story titled, “Study Shows Eldest Children Are Intolerable Wankers.”

Critics of birth-order theories note that it’s not at all straightforward to know what you’re measuring when you try to unravel the factors that shape an individual human life. Lack of a laboratory environment means traits we might attribute to a person’s birth order may in fact have more to do with, say, socioeconomic status, the size or ethnicity of the family, or the values of a particular culture. More recently, scientists note that it might be our expectations and labels that define the roles, and certain personality traits, of our eldest and youngest children, as opposed to their birth order.