Well, it's refuting a lazy argument. Why would computer science be so different from other STEM fields that have radically higher proportions of women? [0] In particular, why is math so much better? [1] If biological differences are so important, why has it varied so much over time, including a big decline since the 80s? [0] I mean, we know that gender roles play a big role in what jobs people do and that sexism is a problem in tech, so it's honestly kind of weird to think "actually, it's mostly caused by some hitherto unobserved large biological difference."
Nonetheless, there is research indicating gender differences in math vary greatly between countries and appear to be correlated to other measures of gender equity [2]. Even in countries with relatively large discrepancies, there's not a big difference. I couldn't find any meta analysis of specifically programming skill, but an analysis of one CS department didn't find gender differences due to ability [3]. An older study showed women and men scored similarly on an introductory class, but women were less likely to get an A or A+ [4]. A small study of elementary students showed that girls and boys did equally well on easy problems, but boys did better on hard problems [5].
[0]: http://www.npr.org/sections/money/2014/10/21/357629765/when-...
[1]: Compare these tables for math and computer science: https://www.nsf.gov/statistics/nsf13327/pdf/tab34.pdf and https://www.nsf.gov/statistics/nsf13327/pdf/tab33.pdf
[2]: http://psycnet.apa.org/journals/bul/136/1/103/; PDF https://www.researchgate.net/profile/Nicole_Else-Quest/publi...
[3]: http://www.pd.infn.it/~lacaprar/ProgettoScuola/Biblio/gender...
[4]: http://files.eric.ed.gov/fulltext/ED384389.pdf
[5]: http://ase.tufts.edu/DevTech/publications/Sullivan_Gender%20...
Nonetheless, there is research indicating gender differences in math vary greatly between countries and appear to be correlated to other measures of gender equity [2]. Even in countries with relatively large discrepancies, there's not a big difference. I couldn't find any meta analysis of specifically programming skill, but an analysis of one CS department didn't find gender differences due to ability [3]. An older study showed women and men scored similarly on an introductory class, but women were less likely to get an A or A+ [4]. A small study of elementary students showed that girls and boys did equally well on easy problems, but boys did better on hard problems [5].
[0]: http://www.npr.org/sections/money/2014/10/21/357629765/when-...
[1]: Compare these tables for math and computer science: https://www.nsf.gov/statistics/nsf13327/pdf/tab34.pdf and https://www.nsf.gov/statistics/nsf13327/pdf/tab33.pdf
[2]: http://psycnet.apa.org/journals/bul/136/1/103/; PDF https://www.researchgate.net/profile/Nicole_Else-Quest/publi...
[3]: http://www.pd.infn.it/~lacaprar/ProgettoScuola/Biblio/gender...
[4]: http://files.eric.ed.gov/fulltext/ED384389.pdf
[5]: http://ase.tufts.edu/DevTech/publications/Sullivan_Gender%20...