Open source software isn't a zero sum game. When one person joins, that does not displace someone else who would normally gravitate to that field because open source can scale efficiently to any number of contributors.

On the contrary, not having enough diversity can and does put off those who would otherwise make great contributors.

Are there differences between genders? Sure. It's an open question how much of the differences are due to direct biological causes and how much are due to societal norms (I find the parallel between open source software and indigenous gift cultures to be quite interesting, for example), but there are certainly differences.

As such, I would oppose any attempts to establish quotas or even aspirational targets for diversity; as you say, forced diversity has negative consequences -- not just for the organization, but also for the individuals involved.

But as much as we shouldn't be trying to bring in individuals who aren't really interested, we need to make sure we're not keeping out individuals who are interested... in a sense, it's more important to look diverse than it is to be diverse.

Hormonal effects has a long history of being overstated and overused when looking for cause in human behavior. It has been used to argue that women aren't fit to vote, then later that they are not fit to hold professions where a stable emotional state is required, to later conclude that estrogen effect on emotional states is complex and what people at the time attributed to estrogen was primarily cultural expectations rather than actually brain chemistry (concluded with some really interesting studies). One conclusion that a profession said that always made good sense to me is that sex hormones are intended to regulate effective reproductive success, not to regulate emotions in women or violence in men.

For example, there was a study done on violent men in prisons and testosterone. The theory that was tested was if testosterone levels were indicator of more violence, for which the data revealed was not the case. Further studies showed that so long testosterone is within natural occurring levels, aggression was not effect by testosterone.

In the context of open source contributions, no one is displaced.

In a wider context, yes, it's a bit more complicated, but Free Software? As a movement, there's power in numbers, and looking to increase that number via a focussed effort on minority groups is simply a smart move.

> First on sex/gender: I feel that hormonal differences create psychological differences in the norms between genders. This is why men are generally more aggressive and violent(see higher incarceration rates) and women are more nurturing.

There's strong evidence that genetic differences account for some behavioural differences between men and women. The ones you suggest do make it clear why you'd expect a skewed distribution of genders in fields such as the army or midwifery. It's much less clear that genetic differences should lead to such an underrepresentation of women in tech fields; in this case I suspect that culture and social inertia are a large part of the explanation.