cold stricken and jealous of brothers from the south

i was born in east india and have lived mostly in north and east india till now. north india gets very cold during the winters and its a common knowledge that south india does not experience as much cold as north india.

here at iitk there is a sizeable south indian population and the most amazing thing is that these guys are seen in a single t-shirt most of the winters. common sense tells us that these guys must feel more cold compared to north indians but such is not the case.

we north indians or east indians can easily be identified by our double sweaters, woolen caps and gloves quite easily. i m yet to meet a single south indian here who OWNS a full sleeves sweater. my eyes open wide is dismay and disbelief if i catch a south indian sporting a winter jacket.

is it the food they eat or the different chemical constitution that causes this? god knows i have wanted to find out the reason for a pretty long time.

any suggestions ???