Rag,
Merely because the man has darker skin you immediately describe him as a Pakistani.

You have a racist's obsession with skin colour.
That is not where anyone's heritage comes from!

It comes from being born or adopted into a family of that heritage and growing up within that culture, like both Khan and Yasmin Alibhai Brown.

That is why she describes herself as "Pakistani," though she was not born in Pakistan, is a British citizen and is married to an English man.
Does that make her a racist, silly boys?