CaucAsian

One of my Japanese friends once asked me if I could tell the nationality of a European person just by looking at them.
I thought it was an odd question and replied that that would be very difficult. In some cases, of course, you might have a typically-looking Italian person, maybe with dark hair and a slightly more tanned skin, and a typically Nordic person with blond hair and blue eyes. But that would by no means be the rule and it would be very difficult in a line of ten people to get all the nationalities correct.
My Japanese friend told me that in Asia, it was quite easy to tell the nationality of people, and I realized of course that he was right. It seems almost kind of odd to me now that in Europe, this is not really possible.
It is an interesting issue. Is it because the European peoples have interbred more than the Asian peoples, so that now it is really hard to tell them apart?