For years, Jessica Krug stood at the front of a classroom and told students about her struggles growing up as a black woman in America.

But the professor was, in fact, hiding an extraordinary lie: she is not black. In reality, Krug, who taught classes on African and Caribbean history, is a white woman from Kansas City.

Admitting the truth in a blog post last Wednesday, Krug wrote that her behaviour was "the very epitomeA perfect example. In her blog post, Krug apologised to all the people she had harmed, both individually and collectively. of violence, of thievery and appropriation, of the myriad ways in which non-Black people continue to use and abuse Black identities and cultures".

According to Krug, her actions are the result of mental health issues and childhood trauma. But in recent history she is not the only white American to take on a new racial identity.

Her case bears a striking similarity to that of another woman: Rachel DolezalIn the five years since she became a household name, Rachel Dolezal has changed her name to Nkechi Amare Diallo and become the subject of a Netflix documentary., a race activist and college instructor, became notorious in 2015 when her parents outed her as white.

Despite widespread criticism, Dolezal remains unrepentant. She claims that "the idea of race is a lie" and says it is possible to be "transracialThe word transracial actually originates from adoptive and academic circles, where it is used to describe the experience of children raised in homes that are racially or culturally different from that of their birth." - just as it is possible to be transgender.

In the same year another US college, Dartmouth, fired the director of its Native American Program, Susan Taffe Reed, after she was accused of misrepresenting herself as an indigenous American.

Today, it is widely accepted that it is OK to change your gender identity. So what is the difference between changing gender and changing race?

The science behind transgender identity is far from definitive. While most studies seem to corroborateSupport a statement or theory. It comes from a Latin verb meaning to strengthen. the idea that there are clear differences between male and female brains, scientists have rejected absolutely the notion that such differences exist between different races.

Indeed, when Rebecca Tuvel, a philosopher from the University of Rhodes, argued that "society should accept an individual's decision to change race the same way it should accept an individual's decision to change sex", she faced a huge backlash.

For Meredith Talusan, a transgender writer: "The fundamental difference between Dolezal's actions and those of trans people's is that her decision to identify as black was an active choice, whereas transgender people's decision to transition is almost always involuntary."

Both Krug and Dolezal built entire careers upon their new perceived identities. In comparison, transgender people often face violence and discrimination.

Some commentators say that while race can be fluid, the actions of Krug and Dolezal are still wrong. White Americans do not experience the everyday racism faced by black people, such as profiling and police brutalityOnly 13% of the US population is black, but black Americans make up over a quarter of the people who have died in US police shootings since 2015..

"Race is a social constructionAn idea that has been created and accepted by the people in a society. Some people believe race, gender and concepts such as masculinity and femininity are all social constructs., but it's real in the way that people treat you," says sociologist Charles Gallagher.

Whereas the mixed-race children of black slaves sometimes chose to "passEven though the "one-drop rule", emerging from Southern states in the US, meant that the nation defined mixed-race descendants of slaves as being black, many were able to enter white society. For some, passing as white and uplifting other black people was the best way to undermine a racist system." as white to escape discrimination, the same cannot be said for white Americans today who pass as black.

Yes, say some. We are living in a world with an increasingly fluid approach to self-identity. Everybody should be allowed to express themselves in any way they desire. Many now even believe that race itself is little more than a social construct. The actions of people like Rachel Dolezal or Jessica Krug are unusual and shocking - but ultimately harmless.

No, say others. The idea of a white person choosing to live as a black or indigenous person is highly offensive. By pretending to be part of somebody else's culture and somebody else's struggle, white people who claim to be black are demeaning the real experiences of African Americans. As Jessica Krug herself puts it: "Intention never matters more than impact."