Ironically, I thought of this idea while playing Spore.
I thought about how creatures appear to be asexual, and while Spore did this to secure an E rating as well as the casualization of the game that we all saw from the 2005 demo, I am 99% sure we have discussed that we will have reproduction as a part of the organism editor.\
And this is where I lead to this topic.
I think that a male v female "slider", based on what the stronger sex is, will have a high impact on how the race acts beyond the organism section.
And to keep this quick, I will present 2 ideas on how I personally believe how it should work.
1). Player Choice
When I say choice, I mean that the player will choose to play as a male or female character (assuming your species has gender). Now when I say choice, you pick your gender as stated above. However for this to have any effect, we would have to have a stereotypical gender based bonus system. The one I think of is females are more diplomatic while males are more war-based.
2). Auto-Evo
Again, we would have to have some sort of effects for the male v female bonus effects. Auto evo would essentially determine which gender should be larger to see what survives better. Now this is just a basic factor, but female T-Rexes and Praying Mantises come to mind in species where females can be more "aggressive". In the mantis example, you could have it to the point where males are literally only used for breeding and as army levies.
Again with the auto-evo situation, the game would have to randomize which bonuses go to which gender. Look at the praying mantis again, Females could be diplomatically advanced, and the reason males are only used for breeding and army levies because they are extremely aggresive. (Not sure if male mantises are like that, just using that as an example)
Now, what are your thoughts on a system like this? I know that the programming part is far off, considering microbes will probably only be asexual.