May be. I probably seek jacket on <15C~20C. But I think it also depends on the body mass, and probably this is the reason people from cold climates are often ta

May be. I probably seek jacket on <15C~20C. But I think it also depends on the body mass, and probably this is the reason people from cold climates are often taller/healthier. With that size the the amount of heat that those bodies generate can only be sustained in an environment that cold. This was very apparent from the dress and shoe sizes available in UK and I have seen the similar from US.