According to Tan Chaoyun, teachers at a local primary school were worried that people would not be able to tell the difference between her four six-year-old sons.  "They are identical, even to me", she said, adding that the only difference between them is the shape of their eyelids.

This has led to some problems when it comes to keeping the children under control.  "Their father [has trouble] telling the differences among them," Tan revealed. "Sometimes he would punish the second one for the third one's mistake."

When the boys were younger, Tan resorted to using ankle tags to tell them apart. Now she has taken a more drastic step to distinguish the boys from each other. "Teachers and classmates can't get confused with the big marks on their head," she added.