For most of history, psychologists thought of the study of siblings as backwater: Parenting was important ”” siblings were not.
Then in the 1980s, a researcher named Robert Plomin published a surprising paper in which he reviewed the three main ways psychologists had studied siblings: physical characteristics, intelligence and personality. According to Plomin, in two of these areas, siblings were really quite similar.
Physically, siblings tended to differ somewhat, but they were a lot more similar on average when compared to children picked at random from the population. That’s also true of cognitive abilities.
“The surprise,” says Plomin, “is when you turn to personality.”
Turns out that on tests that measure personality ”” stuff like how extroverted you are, how conscientious ”” siblings are practically like strangers.
My mother, now approaching 93, said she was always taken by the extent to which her children’s personality was revealed in how they gave up the bottle.
I chewed the end off the nipple to increase my flow rate.
My younger sister very carefully unscrewed the lid.
And the youngest just heaved the bottle across the room.
Some sixty years later, I’d say that’s about right.
That is the funniest thing I’ve read for a while Bart Hall, and perceptive to boot. Thank you.