Which box do you tick on forms that ask for your ethnicity? I go for “Mixed [white/Asian]”. Because this is an option on most forms, I’d never really questioned it, or thought about how it would feel if I didn’t fit into any of the categories. My mother, however, speaks of how much she hated classifying her children as “other” before “white/Asian” made it on there.

Certainly, the word “other” has powerful negative associations. Perhaps that is why the list of options on the census form – which many other forms emulate – prompts such strong feelings. Interestingly, ethnicity data for the UK entirely relies on people’s self-definition. The Office for National Statistics explains:

Is a person's ethnic group self-defined? Yes. Membership of an ethnic group is something that is subjectively meaningful to the person concerned, and this is the principal basis for ethnic categorisation in the United Kingdom. So, in ethnic group questions, we are unable to base ethnic identification upon objective, quantifiable information as we would, say, for age or gender. And this means that we should rather ask people which group they see themselves as belonging to.

Having never had cause to question my own identity in this way, I’d always assumed that ethnicity was tied to race, while nationality denoted one's country of birth. But the term “ethnicity” is actually more slippery than this. The dictionary definition is “large groups of people classed according to common racial, national, tribal, religious, linguistic, or cultural origin or background.” This gives leeway for a whole set of identities to come under the bracket of “ethnicity”.

The debate that preceded last year’s census sheds some light on this. The National Association of British Arabs was active in campaigning for a new tick-box category of “Arab” to be introduced on the form. An article by their chairman set out their arguments:

The lack of recognition of Arabs as a separate ethnic group, and hence their exclusion, has serious consequences for the planning of services and monitoring of such problems as racial discrimination.

In areas where there are large clusters of Arabs such as central London, health authorities and educational bodies have taken such steps as translations of health guidance material in Arabic and the provision of translators in hospitals to cater for this.  However without more accurate data, such services will remain haphazard.

The campaign was ultimately successful, and “Arab” was included on the 2011 list, along with “Gypsy/traveller”, an ethnic group to which many of the arguments above apply.

No-one would dispute that Arabs – united across countries by a common language and culture – are a distinct ethnic group. But this simple notion of ethnicity is problematised by another campaign: for recognition of the “Cornish” as an ethnic group. MPs rejected a bid to include it as a tick-box option on the 2011 census. In response, Cornwall’s local government launched a campaign to encourage people to choose the “other” option, and write in “Cornish”. My first thought on reading this was that “Cornish”, surely, is a regional identity, rather than an ethnic one, but that stems from my assumption that ethnicity is tied to race. Certainly, Cornish separatists would disagree. The bid for “Cornish” ethnicity was based around the region’s distinct identity and language (though few speak it as a first language), and had it been successful, would have accorded Cornish identity a similar status to Welsh or Scottish.

Coming back to the dictionary definition above, this could well be considered valid. The common parlance of “ethnic prints” and “ethnic jewellery” associates the word with foreign cultures – indeed, “otherness” – but this is a non-starter: what makes a samosa more “ethnic” than a cream tea, if you think about the word meaning?

The far-right British National Party defines itself as the party of the “ethnic British”, as set against “ethnic minorities” who are supposedly taking over. But the fact that hundreds of thousands choose to describe their own ethnicity as Welsh, Scottish, or Cornish shows that “ethnic British” is a nebulous concept. Given that “ethnic” can refer to “regional” or “linguistic” groupings, who is to say that someone who is black but born and brought up in Britain cannot be ethnically British and ethnically Nigerian (for example) at the same time?

The box that you tick on a form might, on the surface, appear to be meaningless bureaucracy. But it goes right to the heart of national and ethnic identity, a burning issue for many people. Inclusion on the census form indicates whether the state accepts your self-definition; personal though it is, by definition, associating yourself with a particular group also makes an outward statement. Forced to make a choice, most people will go with the most literal option – eg. their race or country of origin. This makes sense: the nuances of self-definition and ethnicity are too wide-ranging to fit into a tick in a box.