His research has covered feminism, swinger clubs, transgender, nudists, sexuality education and masculinity.

He used to identify himself as a "feminist", but says this has been twisted as a term for extreme people fighting for female-dominated society. Now he calls himself a person who supports equality between men and women. In September, a non-government feminist organization New Media Women Network published a statement calling on schools to set up a system to stop sexual assaults.

It came against the background of frequent reports of sexual assaults against students in Chinese schools and universities, and was triggered by reports that a professor at Xiamen University was seducing his female students.

Fang drafted a response to the statement, which was supported by other well-known Chinese sexologists, including Li Yinhe and Peng Xiaohui, advocating empowerment sexuality education for teenagers, letting them have the right to decide whether they want it or not.

"We think teenagers are able to tell the bad from the good, to choose and to be responsible for themselves and others. There is not much sexuality education in China, but traditionally teenagers are told not to do anything related to sex," he says.

The response said "we firmly combat any sexual violence at school," but "based on the situation of sexuality education in China and the expression of the statement, we are worried the proposal may have worrying results".

The response emphasized that their solution is sexuality education rather than simply bans or punishment, which may lead to the violation of other people's personal rights.

Tuesday was the International Day for the Elimination of Violence against Women, and Fang had been busy organizing the Second Annual Meeting of the China White Ribbon Volunteers 2014.

"Equality between men and women can only be realized when men join in. Sometimes domestic violence against women is a result of men's anxiety about their masculinity, which men can free themselves from. There is no need to follow society's requirement that masculinity be defined as strong and dominating," he said.

"All of my research, including on masculinity, lets me know that a real open society should allow sexual plurality, which is not to encourage multiple sex partners, but to respect people's choices."

Contact the writer at yangyangs@chinadaily.com.cn