[bitexploder]

I don't think it is complex. The theme of a social group is just there as a filter. If you like rock climbing and meet someone at a rock climbing gym that person is far more likely to be interested in things you are interested in: physical fitness, the particular mental challenges of rock climbing, etc. It was just an example. I won't analyze the sexism or male only nature of the fraternity, but I think Freemasonry anecdotally reinforces the idea that men want/need/form these kind of clubs more than women on average.

When we study this we notice very small actual bias at an individual level on socialization preference. The differences are modest and more like slight preferences. There is more overlap than not at a local individual level. What gets missed is that even though the differences are relatively small, the network effect greatly amplifies these small variances resulting in non-linear outcomes. Even small biases at an individual level essentially produce significant effect in socialization behavior.

[laurencerowe]

> but I think Freemasonry anecdotally reinforces the idea that men want/need/form these kind of clubs more than women on average.

There seem to be as many Women’s Institute members in England as there are Freemasons.

And that is before you consider more ad hoc organisations like book clubs that are definitely more female dominated (though sports clubs perhaps the opposite?)

[heresie-dabord]

> I don't think it is complex.

I'll defer to you of course if you have personal experience that I do not. But would it not become more complex than a "woodworking club" (men's shed) or than a brick mason's guild as soon as a complex filter such as religion is introduced?

> I won't analyze the sexism or male only nature of the fraternity

No need to analyse the usefulness of fraternity (or sorority), I think. It's just a fact that sometimes the sexes don't want to mingle. What could become problematic are cases of gender-fluidity.