Originally Posted by Doctari
I'd like to throw another theory into the mix: Where you grew up, ie usual (Mean?) Temp. My former work partner (one of my current hiking partners) is from South Florida, He's a bit taller than me, I'm about his weight, similar ancestry (Scandinavian & etc.) but there is a VERY narrow window when we can both hike together. I can't hike above about 90 degrees, Him not below about 60, at least for an overnight trip.
I tend to agree. Not uncommon for temps here to be up over 100 degrees from June through September. Heck, it was 114 the day we got married. I sleep cold and usually am looking for a jacket at temps below 70.
One night, in Yosemite with temps ~32 - 34 degrees I was in my Big Agnes Lost Ranger (rated @ 15*, but B.A. over rates their gear), with an 2.5" down insulated air core pad. I was wearing capilene 3 top and bottoms, fleece jacket & pants, and two pairs of wool socks and a wool hat and could not sleep with all the shivering I was doing.
I'm of Italian / Spanish decent, but my wife who is of Irish / German decent has no problem with the cold.