I went through all 1494 users at https://github.com/orgs/google/people and classified them into Male/Female/Unknown (this took about ten hours). I then used the GitHub API to pull information about each user, as well as contributions data from all of Google's Github repositories.
I'm not entirely sure what to make of these results. They're potentially pretty incendiary, which is why I'm posting under a throwaway. Screenshot: http://i.imgur.com/bJXyTqX.png, OpenOffice spreadsheet: https://filetea.me/#n3wTD4xSK6rTn6xxZMtkxLq2w.
It's pretty easy to grab the data from GitHub's API if anybody wants to try to replicate this.