The paper disappoints me because they attempt to think of all the explanatory variables for the differences between countries, then they turn to gender and end on a chart.It's impossible to read the paper and come away with the impression that whites are simply better at coding, because the authors give so much context to their findings.
I am agnostic to the cause of the gender difference, and clearly this study didn't have enough information to give any insights. That's why I find it so unsatisfying that they would put up a chart and mention gender differences if they weren't interested or capable of expanding on the results beyond "[...] more effort is needed to attract higher-achieving female students into CS."