Twin studies don’t help you with this particular question. Beyond that, there are plenty of scholars who question the common interpretation of twin studies.
https://en.wikipedia.org/wiki/Twin_study#Criticism> all points in the direction of genetic causation when it comes to cognitive traits
To be precise, some evidence points in the direction that some variation in cognitive traits is “heritable”.
It is obvious to everyone that there are substantial effects on cognitive traits due to malnutrition, disease, exposure to toxins, physical violence, persistent emotional trauma, and so on, as well as a substantial amount of variation that we currently don’t have explanations for (not to mention significant experimental noise and epistomological questions about the design and interpretation of the experiments). It is at least plausible that large-scale differences in the treatment of boys vs. girls could have effects on cognitive traits.
For example it was long thought by some people that there were inherent differences between boys’ vs. girls’ mathematical aptitude, as judged by scores on various standardized tests, but in some countries with more equal social/educational environments those differences in scores entirely disappear. A web search turns up https://insight.kellogg.northwestern.edu/article/women-and-m...
> I recommend reading the Jensen’s 1998 book
It should be mentioned that Jensen’s work has been highly controversial and has kicked off a lively debate. Some of the biggest promoters of Jensen’s work have been quite unsavory characters. Like all scholarly work (and especially all work seized on more by activists than scholars) it should be read critically and taken in the context of a wider discourse.
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Disclaimer: I am no expert on this subject. Just a layperson who has occasionally read about it, mostly in popular media.