Gender identity made headlines in Ontario this week, after a Progressive Conservative resolution introduced at a weekend party convention called the theory a "highly controversial, unscientific 'liberal ideology.'"

Ontario Premier Doug Ford quashed it days later, but behavioural neuroscientist Sari van Anders argues that the relationship between sex, gender and biology has long been understood to be more than a simple male-or-female binary.

"The idea of female and male brains is outdated and never reflected the science," van Anders, the Canada 150 research chair in social neuroendocrinology, sexuality and gender/sex at Queen's University, told Quirks & Quarks host Bob McDonald.

"It's not a one size fits all when it comes to your sex and gender."

Indian transgender activists hold a vigil to mark the Transgender Day of Remembrance in Hyderabad. The day is marked worldwide to remember members of the transgender community who have been murdered, and to raise awareness of the threat of violence and persistence of prejudice felt by the transgender community. (Noah Seelam/AFP/Getty Images)

Sex refers to the physical aspects of a person, such as genitalia, hormones, sex diversity, gonads and secondary sex characteristics. It is typically determined at birth, usually by looking at a person's genitalia.

"I think people think that sex is the simple one and gender is the complicated one ... even as we know that they often exist in different ways and there's multiple aspects of each," said van Anders.

"People are expected to move through their life in the world in accordance with whatever that identifier is. But as we know, for many people that doesn't work out."

Gender is sociocultural, and refers to things like clothing, behaviour and whether someone acts according to feminine or masculine norms. What exactly shapes a person's gender is still unknown to science, said van Anders.

"It's really just sort of understood to follow from sex, even as we understand scientifically it often doesn't."

Biology versus psychology

Van Anders led a recent study looking at the relationship between the "masculine" hormone testosterone and behaviours such as competition and aggression.

She found that the act of engaging in these behaviours was enough to increase testosterone in both men and women — meaning the behaviour was affecting hormones, instead of the other way around.

"So we know that living life as women or men, or as non-binary people, and the gender norms that that involves, can actually influence the ways our hormones act."

Joshua M. Ferguson who received Ontario's first non-binary birth certificate talks to media at the Human Rights Monument in Ottawa. (Sean Kilpatrick/Canadian Press)

Even with the science of gender still unclear, said van Anders, the idea that biology dictates behaviour is often proven wrong.

"They've done that with women saying, 'Well, women have uteruses and somehow that pulls all the blood from their bodies from their brains and they can't actually study,'" she said, referring to the incorrect historical belief that the uterus was responsible for a wide variety of ailments including fevers and kleptomania.

"I would say that genitals matter, but they're not determinative. And I think that's the key."

'Trans is nothing new'

According to van Anders, evidence of trans and non-binary people have been found dating back thousands of years. Pottery found in ancient Egypt dating back to the year 2,000 BC shows depictions of three genders.

"Trans is nothing new," she said.

"Transgender people, living in genders that branch from what they were assigned at birth, have been around a long, long time. Various indigenous nations have diverse gender experiences, including what is now called two-spiritedness. Cultures in Eastern Europe, East Asia, all over the world have multiple genders or third genders."

Critics say motions like the one put forward by the Ontario Progressive Conservatives, even if it was quashed by Ford, are still damaging to the community.

Lyra Evans, the first openly transgender school trustee in Ontario and possibly in Canada. (Adrian Wyld/Canadian Press)

"It really shows that there are segments of the population who do not want trans people to exist," Ottawa school trustee Lyra Evans, who is transgender, told CBC News.

"A lot of trans people that I've spoken to, they're scared," she said. "It's a group of people who are likely to face employment discrimination, housing discrimination, and mental health issues."

Van Anders agrees.

"I do think transgender, intersex, and non-binary people are the experts on this one. And they tell us how dehumanizing it is and how negative the impacts are," she said.

"We know that debate of your existence, much less your human rights, isn't really good for anyone."