I have maybe 5% Italian. My paternal grandparents were both full-blooded Irish, as was my maternal grandfather. My maternal grandmother was mostly Irish, with some Italian blood back to her great, great grandmother.
So, BZZZT! wrong again! And you're wrong about Asians...many Japanese and Koreans are lactose intolerant. So, if I'M the culprit because of my 5% Italian blood, AND my older son is fully 1/2 Japanese, then why didn't he get colic? Seems much more likely than a boy who's 1/2 Swedish 1/2 Irish. Next you'll be telling me you can catch cold by going outside with wet hair...