Only with such a tidal wave of change was Cook able to reveal his homosexuality without worrying about his career being destroyed.

Because Tim Cook is one of the most outstanding chief executive officers in recent history, his decision to announce that "he is proud to be gay" will probably help make not only American society but the world at large more tolerant to these issues.

Will China go through a similar evolution?

Homosexuality in China has been documented since ancient times. Many Chinese emperors probably had both homosexual and heterosexual relationships. As in ancient Rome, homosexual relationships in China were frequent but were not considered morally deviant before the influence of other cultures.

In 1997, the national penal code was revised in China making adult, consensual and non-commercial homosexuality legal in the country. Only in 2001 was homosexuality removed from the list of mental illnesses in China, and the public health campaign against the HIV/AIDS pandemic includes education for men who have sex with men. Police enforcement against gay people is limited to gay people engaging in sexual acts in public or in prostitution, which is also illegal for heterosexuals.

In February this year, a man named Zhao Peng sued 58.com, an e-commerce company, saying he was refused a job because of his gay identity. The employer explained it refused Zhao not because he is gay, but because his bold showing-off of his "gay identity" was contradictory to corporate culture. The court didn't intervene but asked them to turn to labor arbitration.

In China, lesbian, gay, bisexual and transgender people's working rights are still quite vague, because as a social group their rights as a whole are still not upheld by society. Cook's courageous words may provide the impetus to change attitudes. Hopefully in Chinese society sexual orientation will not hinder one's career, either.

The author is an international public health consultant and a winner of an Overseas Press Club of America award.