This is a big topic, which I don't feel I can do justice to, but here are a few thoughts nonetheless. It's also important to see how resort to biological arguments could help to perpetuate such gender differences.
Brain is not behaviour
Brain differences are irrelevant if they do not manifest in behaviour. Thus, to show that size of structure of the brain varies between genders may be suggestive. However, to use this to explain gender differences in the historical differences in inventors is a big leap.
Empirical evidence for gender differences
The best data I've seen examining the size of gender differences on a wide range of psychological variables was the summary of meta analyses by Hyde (2005).
Hyde puts forward
the gender similarities hypothesis, which holds that males and
females are similar on most, but not all, psychological variables.
Results from a review of 46 meta-analyses support the gender
similarities hypothesis. Gender differences can vary substantially in
magnitude at different ages and depend on the context in which
measurement occurs. Overinflated claims of gender differences carry
substantial costs in areas such as the workplace and relationships.
In particular, check out the first section of Table 1 of Hyde (2005) where you can get a summary of meta-analyses of gender differences in cognitive ability. In general the differences between males and females tend to be fairly small, and there are several meta-analyses that found females to have slightly superior ability to males. Furthermore, such studies don't prove whether the generally small differences observed will change in the future should society change in its treatment of males and females.
What makes a great inventor?
I imagine that all sorts of factors related to social context, individual traits, and learning experiences would be related to the emergence of great inventions.
Furthermore, the emergence of great inventors is often seen within a broader historical context, which encompasses periods of time where women's access to education, access to career opportunities, and role expectations provided minimal opportunity to become a great inventor.
I think the expertise literature would provide a reasonable lens for thinking about what it takes to become an expert. E.g., check out some of the articles by K. Anders Ericsson. It emphasises the importance of spending thousands of hours of practice and effort in acquiring the skills required to become an expert.
Thus, we might switch the question around to say, what causes someone to spend thousands of hours devoted to learning and developing skills relevant to making a great invention?
- Hyde, J. S. (2005). The Gender Similarity Hypothesis. American Psychologist, 60, 6, 581, 592. PDF