To my knowledge the Hewson name (like mine, Henson) is quite English, Evans is more a Welsh name, I think Clayton is a Scotish name, and only Mullen is an Irish originating name.
I could be wrong.
They dont even have Irish accents, now and then Bono breaks into semi-Irish accent when he talks, but who are they kidding :b
I'd be interested in knowing their ancestery, but i'm a lazy git, so anyone that knows any, do tell. Thanks.
p.s, someone who no-longer like U2 it seems: http://www.geocities.com/SunsetStrip/Palms/4845/u2page.html