Mmmh in my head it goes like this : Kyle would have mixed origins, like maybe British / Vietnam. Both of Nate’s parents would be British but he would have Italians ancestors. Darren would come from the north of Africa and be a few shades darker than his mates. Maybe Egypt
As for their height, I would say Nate is the smallest (around 1.75) and Darren the tallest (around 1.85)