I believe that a significant factor for this can be attributed to mental development and maturity of boys lagging behind that of girls of the same age, during formative years. And, please read on, if you assume my argument is "boys dumb, conservatives dumb. Q.E.D."

The second factor is an education system where this offset in mental development/maturity is further confounded. Boys don't typically do as well, because sitting idle and being a "good boy", is more challenging. This leads to a path for boys to start working earlier, while girls get higher degrees. (I assume the trends for higher education by gender, to be similar, if not, then that can falsify this hypothesis).

What a person then observes they get from society, vs what you pay in terms of taxes, is skewed between these two groups, and highly correlated with gender.

If this hypothesis has any validity to to it, then one could argue that a way to mitigate this is by correcting the negative causes. Where the fundamental root cause might be improved by revisiting how education is failing boys in particular.

The challenge with this is that if the conservative parties' policies are driven by what can make more people vote conservative, then this will be a negative feedback loop. The worse you make it for a certain group of people that vote for you, the more that group is willing to vote for you.