I'd imagine most people who have access to a computer at the age before they start working(<22) in a country like India are also people who come from a ridiculously elitist economic section of the people considering the average per capita income is about Rs. 35-40,000. (700-800 USD per annum)
Not saying they're directly co-related, that'd be stupid and it certainly wouldn't explain an average height of 6'0 on CW but it makes logical sense that the average height of a CWer is more than the average height of an Indian, on a general level.
Personally, I'm 6'0(and a half), have about 3-4 guys in 40 more guys in my batch who are the same height or more. However, I'd say the average in my college batch is around 5'8 or so which is still significantly more than the statistical average. This observation is approximately true for my class 12 batch as well. A guy who is 5'4 which is supposedly average would certainly be considered short, to be honest. Again data effected by urban, richness bias.
It's truly bizarre and I was shocked when I first found out that the average male height in India is 5'4.