From Mechanical point of view there is easy solution for this problem. No modifiers, except racial pluses and minuses. But how to diffrence genders on mechanical level ?
Well ... there is mechanical way, building points for nations and rough desriptions of gender roles in society.
For example in patriarchal society, where menfolk work in the field while women tend the homes and manage children. Menfolk would build up more their Strenght and Charisma, first to be useful for the society, second to dominate over other males. Among those who are at the top, excepted is that they are the most Charismatic and Strong, Tough and Wise. Or at least Smart. Guy have to be a winner, or will be replaced with someone more suitable.

Womenfolk are expected here to be Wiser, capable of managing the mess that menfolk leave after them. So my choice will be giving points in Constitution and Wisdom.

And good new, since they are not excepted to dominate in, boys only club, they have less worries about social position.
Second example, menfolk are crafters and caretakers, womenfolk rule and serve in army. Boys will need Inteligence, and Dexterity for their crafty work, and Wisdom to manage conflicts among children/animals/pets/slaves left in their care. Their position depend on how important their wife/owner/mistress is making them proud and dominating in their "circle" as well as their own skills wich are giving them their position on the "top" among other crafters.
![Devious :] :]](http://www.enworld.org/forum/images/smilies/devious.png)
Girls will build Strength, for obvious reason"We are beating them into the ground with strength of arm, not charm of good heart".
Constitution, because martial training will kill all weaknesses and I doubt that in team would be tolerated someone worthless from military perspective.
Charisma, leaders must have "this something" that make people obey, don't You think ?
Obviously both my examples are bit extreme, with very strictly divided roles for genders. Assuming that particular race have just two genders.
My final note ? People change to fit to their environment, I would surely say no to flat rule that Men have +2 Str, Women +2 this, and +2 that so they would not feel discriminated. No, No, No.

This is discrimination of menfolk ! We are not just stupid brutes incapable of speaking coherently like such ruling would suggest. Belive me.
In my opinion it should depend on cultural limitations and roles how genders build up their atributes/abilities, and I say no to flat unchangable rules ... because they rob us of diversity. Howgh.
