“别人家” means “other families,” and “孩子” are “kids.” Literally translated as “other people’s kid,” this term actually refers to those who have been excellent in many aspects (especially academic performance) since childhood and are often mentioned as role models by other parents to spur their own kids to work harder. This expression jokingly reveals the fact that many Chinese parents are keen to compare their own children with other kids, and not very good at seeing the merits in their own offspring.
Zhècì zhōngxué tóngxué jùhuì nǐ jiàndào dāngnián de xiàohuā le méi？
Did you meet the campus belle at the gathering of our middle school classmates?
Jiàn dào le，tā háishì nàme měi。Tīngshuō tā zài yīsuǒ zhòngdiǎn dàxué yǐjīng píngshàng jiāoshòu le。
I did. She’s as beautiful as before. I’ve heard that she is already a professor at a key university.
Tā cóngxiǎo jiùshì biérénjiā de háizi。
She’s been outstanding since childhood.