I once had a theory that people from England came over to Canada with a kind of resistance to the cold winters over here. I, like many, grew up in Brit houses with no central heating, and with one coal fired fireplace to heat the whole house. I found my first couple of Canadian winters to be no trouble at all (I came over in 1966). The Canadian
homes I lived in had central heating and were well insulated. Then after a couple of years I started to notice the cold. My child's mind saw this as my blood having become 'thinner'. Now I think that maybe my reliance on central heating lowered my resistance to cold temps.