PARIS, June 28 -- When summer temperatures rise, not everyone handles the heat in the same way. Some people breeze through scorching days, while others seem to wilt in the warmth. What lies behind these different coping abilities? The answer can be found in a combination of physical traits, genetic influences and behavioural habits

When the warm weather arrives, two distinct camps emerge: those who love the heat and those who hate it. And each tribe has its own rituals and interests. The former dream all year round of jetting off to sun-soaked destinations, while the latter head for northern climes to avoid scorching temperatures.

A matter of taste, some would say. But also of physical constitution. Indeed, we're not all equal when it c...