AFAIK the IQ difference between genders is negligible, but the spread of the IQ is much greater in the male group. This also means that there are more men who are above 130 IQ then women which is kind of necessary to be a programmer. This does not mean that a female can't be a genius! If you want to disprove this you can do two things: 1., Prove that the average female IQ is way higher than mens. 2., Prove that there are as much women who are intellectually retarded ( sorry, English is not my first language, I don't know a better word ) than woman.
Wait, what? What exactly do you think the IQ of the average programmer is?
Therefore it is not unreasonable to deduce that people who work as programmers in prestige companies are, on the average, from the very right-hand tail ends of the normal distribution curve, and the differences of men and women (on the average, again) are significant enough to cause an over-representation of men among this group.
The same thing that causes an over-representation of men among homeless alcoholics at the left-hand-side end of the normal distribution.
[0] https://qz.com/334926/your-college-major-is-a-pretty-good-in...
The problem is that Google already does do this, for the most part. So what does it mean to say that Google ought to treat people as individuals, if that is already the current state of affairs? The argument, as coded in the document, was that Google ought to cease making any efforts to correct disparities in representation.
As a moral or rational argument, this falls flat on its face. Suppose that there was science to show that cognitive differences between men and women or different races is 100% inborn (there isn't, not even close). Even then, there's still the problem of whether the magnitude of those differences justifies the magnitude of differences in representation. There is not nearly enough data to make a case here, and by presenting the case as made, the author of the doc was doing more than just observing the state of the science. He was making an unsubstantiated claim that his coworkers, or at a minimum the sex and/or races they belong to, are inherently deficient at performing the work.