Researchers at UC Riverside, the Oregon Research Institute and the University of Oregon figured this out, with the help of a National Institute on Aging grant, by analyzing teacher personality ratings of children along with videotaped interviews of those now-adults four decades later.
Here are the personality-trait findings as described (very briefly) in the study's abstract, published online last month ahead of print in the journal Social Psychological and Personality Science. And here are the personality-study details as presented in the UC Riverside news release. Plus the Vancouver Sun's summary: "Personality Takes Shape at an Early Age."
As to who is surprised by these findings, that would apparently be the researchers.
Not me. I've noticed my former classmates and childhood chums—not to mention that brother of mine—all have precisely the same character flaws they had as children.
The researchers say, however, that further research could determine how people can change their personality. Ah, so there's hope ...