"Tamilnadu guys" or just "Guys"?

Hi all..
I find a phenomenon in Tamilnadu guys(I dont really know whether it is the same case with other guys as well...)
They are soooo withdrawn...in the sense, they find it extremely difficult to talk with girls...Ya..they are street smart and all...but when with a girl, no ...they can better themselves...There is this guy in my class, who should interact with me for certain official reasons, he sees to it that he never calls me by my name(for that matter, any girl by her name...)....even when he has to pass on something to me from a couple of benches to my back...he would not call me, rather, he would come all the way and hand it over without an extra word...And mind you, this not an isolated case...happens pretty often...
But I know that these guys are not shallow at all. Only with the opposite sex...they are drawn back...They have a voice only when they are in a group of their own kind...never an individual move...
On the other hand i see that girls are pretty open...in their convertational outlook.
And people, please don't pervertise this. I am telling it in a well-meaning way.
Of course, there are guys who are pretty fine in this matter....But the other group is definitely not a miniscule portion of the society...
So what might be the reason..?