Something else to think about: yes, there may be a couple of subgenres (UF, romance, paranormal) or marketing categories (YA) where there are more women writers, or where they are more visible. The one thing they all have in common, though, is that they lack prestige. They're niches that even genre fans, who are used to dealing with the disdain of the literary world, often look down on and dismiss as silly. Why do you think that is? The correlation between this kind of attitude and the fact that these are female-dominated niches is enough to ring alarm bells in my head. So even if that study yielded the kind of results you suggest (which yes, it very well could), I don't at all see how pointing out a non-prestigious niche in which results would be different changes the overall trend Renay has shown here.

RE: "This has nothing to do with gender preferences, but just a matter of what's out there that seems interesting.", I have just addressed that here.