Nonetheless, any assumption of Bermudian demographics that is based on census returns, or other sources derived from them, suffers from anecdotal evidence being the basis of all of the data, in asking Bermudians to self-identify, without resorting to any documentary evidence or genetic studies being used to confirm their ancestry, if not their identification. There is similar pressure on Black Bermudians (most of whom are multi-racial) not to self-identify as mixed race as there is in Blacks in the USA, where President Barack Obama, raised by his single, white mother, sparked debate when he identified himself on the census as black, rather than mixed race, and in the UK, in both of which countries greater flexibility is also now allowed for people to describe themselves racially.