Originally, Mr. Kong said this was a problem inflicted on fifth-graders, leading to hand-wringing that Singapore children were way better at math than everyone else in the world and worries that Singapore children were being mentally abused with convoluted logic at a young age.
It turned out the problem actually came from a math olympiad test for math-savvy high school-age students.
People may unsuspectingly choose friends who have some DNA sequences in common with them, a new analysis finds.
Researchers compared gene variations between nearly 2,000 people who were not biologically related, and found that friends had more gene variations in common than strangers.
The study lends a possible scientific backing for the well-worn clichés, "We're just like family," or "Friends are the family you choose," the researchers said.
"Humans are unique in that we create long-term connections with people of our species," said Nicholas Christakis, a social scientist at Yale University involved in the study. "Why do we do that? Why do we make friends? Not only that, we prefer the company of people we resemble."