Why are girls' hands cold?

Every girl I've offered a shake hand, I find their hands are cold. Never encountered the same with boys. Why is it so? And I wonder if they find something like the same when they shake hands with boys... like they find guys' hands hot (no pun intended!!).
Okay I was wondering about it because today morning I met Rachel and shook hands with her, and it was... ICE COLD!! Hmm... She's a girl, so obviously I'm supposed to find her hand cold... I wonder if there are exceptions!!