What's more, her mother and her biological father were never married; morally, the argument goes, this kind of behaviour shouldn't be publicised, so she shouldn't have been put on TV as a young "idol".

Her ugly labels include "black chimpanzee", while the nicer ones describe her as "China's Halle Berry".

These kinds of posts on the most popular chat rooms have attracted thousands of comments. A few have been supportive of Lou Jing, but the rest range from expressions of fear and ignorance to outright racism.

Most of the critics are agreed on one point: that this black woman cannot be regarded as a "real" Chinese.

As recently as the 1970s, foreigners were largely barred from living in China, let alone marrying a local.

China does not easily accept mixed-race children as true-blooded Chinese: as soon as a child is born, the parents are required to register with the authorities as to which of the 56 government-approved ethnic groups their child belongs; there are no mixed-race categories.

As China undergoes an astonishing demographic shift and more foreigners make their homes in the Middle Kingdom, Lou Jing is by no means the only one being treated differently.

Recent decades have seen a surge in the number of mixed-race couples. Shanghai Civil Affairs Bureau data show that from 1994 to 2008, each year there has been about 3,000 more mixed-race marriages in Shanghai.

But as the children of that first generation of mixed-race marriages come of age, their moves to gain acceptance in society - like Lou Jing's participation in the TV show - have exposed a deep-running vein of xenophobia in Chinese society.

Last year, Ding Hui, a young man of African-Chinese ethnicity, caused a stir when he was called up to the national volleyball team, prompting much soul-searching about whether the athlete should be allowed to represent China alongside pure-blooded Chinese competitors.

Eventually, Ding Hui did go on to play for the national team.

"As China continues to open up, this kind of phenomenon will become ever more prevalent," said David Zweig, a professor of humanities and social sciences at the Hong Kong University of Science and Technology.

He told Time: "This is part of the process of internationalisation, but we can only hope that Chinese people, including netizens and the people whose views tend towards extremism, can come to accept that there are many mixed-race people, both in China and worldwide."

As for Lou Jing, she found the whole experience more than a little disturbing. She did well in the show, ranking in the top 30 contestants before she was eliminated.

Now she's back to her normal life as a college junior - with a little new insight into her home.

"Through this competition, it's really scary to find out how the colour of my skin can cause such a big controversy," she said in an interview.