'I didn’t know she was black until a number of years ago when she happened to turn black,' said Donald Trump, recently.

When the former US president called into question Kamala Harris's racial identity, it sparked an angry backlash. The White House press secretary, Karine Jean-Pierre, responded by saying 'no-one has any right to tell someone who they are [or] how they identify.'

Mr Trump's words hit a nerve in the American psyche, tapping into a centuries-old debate about ethnicity and authenticity, power and privilege.

But in an age where it is said that race is a social construct, how fluid is racial identity?

For Assignment, Ellie House travels around the US, meeting people fighting to claim their racial identity - as well those looking to police it. From an organisation that seeks to expose fake Native Americans in North Carolina, to the Ohio town where people with red hair and green eyes still identify as black, due to the racist history of their town's authorities.

‘Please note, this episode contains some outdated racial language that could cause offence.’