There is always a reason. There's always a neural correlate, a psycho-social construct, a genetic component, an environmental variable.

Of course there is.

It would be truly astonishing if there wasn't.

Finding it might prove hard, though. And anyway, so what? If we did find those neural correlates and genetic components we'd... do what, exactly? Invent a pill, a therapy?

In the meantime, we can rationalise simply that xenophobia is destructive, and we can determine effective interventions.

Should we tackle what our understanding currently allows, rather than waiting to uncover an explanation?