Many studies have been conducted on this topic. Many philosophers have wondered why this is so. Many academicians, and academic communities have racked their brains to solve this "problem". What am I talking about? Well, it is the differing interests of men and women (or boys and girls) with respect to science.
Why indeed, 5o years after the gender equality movement, has the ratio of male to female physicists, or mathematicians not changed? Why is it that despite desperate attempts, particularly in the US, not enough women graduate from technical fields? Also, on a complementary note, why is women's enrollment in computer sciences so high, particularly in comparison with other fields in India?
Well, the answer is simple. Evolution has trained women to value social status over academic achievement. Evolutionarily, it was better to be the mate of a high-ranking man than be a brilliant hunter yourself. This guaranteed success of the off-spring, as the man's success determined that of the household.
Now things have changed. However, evolutionary habits die hard. Most women still prize social elevation over everything else. Note the qualifier: "most". There have been (and are) many women who prize academic achievement. But they are the exception and not the rule. So, bottom line, women will go to a field that will enhance their social standing. And for most of them, that is simply what their peers think is nice, or what the men of the day perceive to be "cool".
So, why hasn't women's enrollment in technical subjects increased? Because technical subjects are not perceived as being "cool" in the US. Why is women's graduation rates in technical subjects so low? Because they want to be socially elevated, not academically. And more controversially, why do women flock to computer science courses in India? Because that is the route to social elevation in this country.
Remember that most women who actually get into technical fields in this country rarely stay in them. Even if they do, their levels of accomplishment, in understanding and furthering the field are minimal. [Again, this is true of most women, not all.]
So, why am I ranting about this at 12 midnight? Because I'm fed up of people "encouraging" women in the software field by ignoring similarly qualified male candidates. It hasn't worked, it won't work. Those women who are really interested in getting on the software bandwagon will not need a ladder for it. And those that do, most probably, won't do much getting on the bandwagon.