SPORT makes me tense. It is not the exciting finishes, but the questions it asks about my identity: "Just who d'you think you are, Simon?"

It all started a few weeks ago, when an 18-year-old footballer, Adnan Januzaj, scored a couple of goals for Manchester United. Suddenly, everyone, including the England manager, was wondering whether he could play for England. Residency rules say he can, if he lives here for five years, and suddenly it's all kicking off.

The Arsenal and England player Jack Wilshere immediately took to Twitter - where all serious discussion takes place these days. You should not play for England unless you were born in this country, he said; but, on reading that, Kevin Pietersen, the England cricketer, was furious. Born in South Africa, but with an English mother, he regards himself as English born and bred.

"Interested to know how you define a foreigner," he tweeted in response. "Would that include me, Strauss, Trott, Prior, Justin Rose, Froome, Mo Farah?" These heroes of English sport were all born out of the country, apparently.

It is complicated, being English, with national blood that must include Romans from the first century, Danes from the ninth, Normans from the 11th, Huguenots from the 17th, and West Indians and Ugandans from the 20th - and that was before the EU doors opened.

Someone once told me that the only real English, the Angles, live in Anglesey, pushed there by the Saxon and Viking visitors. So we have always been a melting-pot of nations - an idea that Russell Brand, the comedian, enjoys. On his current tour, he defines an immigrant as "just someone who used to be somewhere else". In our global village, moving country is like moving house.

It is an engaging idea, but it puts a strain on national identity in sport. Thanks to his parentage, Mr Januzaj currently has no fewer than five countries offering him a passport: Belgium, Serbia, Albania, Kosovo, and the UK. Of course, identity is all over the place in the English Premier league - when Swansea (a Welsh club in this English league) played in Europe recently, they had more Spanish players in their team than the Spanish team that they were playing.

But complications are more keenly felt at national level. Arsène Wenger, a Frenchman who has managed Arsenal for the past 17 years, has his own philosophy: "I have players who have three different nationalities. So I ask them, 'Where do you really feel you belong?' At the end of the day, I believe you are from the country where you feel most comfortable with the culture of the country."

So the message is simple: you are English if you feel English, if your heart is here; although I do not see this appearing in many manifestos come the 2015 elections.