Be careful implying causation here. We would want to investigate who identifies themselves as any sex vs who remains unidentified (or less obviously identified) and the skill levels represented in each group. Since GitHub does not request your gender for your profile, they used Google+ profiles, which I think would significantly slew the results; they did not sample from <i>all</i> pull requests, but from those that were linked to a G+ account AND whose owners decided to post their gender.<p>&gt; Specifically, we extract users’ email addresses from GHTorrent, look up that email address on the Google+ social network, then, if that user has a profile, extract gender information from these users’ profiles. Out of 4,037,953 GitHub user profiles with email addresses, we were able to identify 1,426,121 (35.3%) of them as men or women through their public Google+ profiles.