In historical perspective the Vikings used to go over to great Britan and do whatever they wanted to do. So every century when a British do good in the winter olympics then you don't need much fantasy to understand who the grand grand, grand...grand father came from.
Don't ask me about details here.
But nationalism could be dangerous, I believe Einstein once told
"Nationalism is an infantile disease, it is the measles of mankind."
in historical perspective we are all from a adam and eva, the apes, a bacteria or whatever. We are a bounch of monkeys in my view. I like to be a monkey.