Pretty much all gender roles are based on stereotypes. A lot of these stereotypes have biological/evolutionary roots. Last semester, in my educational sociology class, I did an essay on why there's more female teachers than men (especially in primary education). I found that the main reason behind this was that women were perceived as being more nurturing/caring. It turns out that this stereotype developed because during prehistory (and after) women were in charge of domestic issues, whilst men were in charge of going outside and hunting. Why didn't women do the hunting? Biological differences. Men are far stronger, far more capable of hunting. On the flipside, women have finer motor neuron control, which translated into them being more more precise with their hands, which is part of why the stereotype around women being more crafty (in a technical sense) exists.
Basically, a lot of the stereotypes and gender roles that exist around men and women are founded from biology and evolution.
Disclaimer: Before anyone jumps down my throat for being a SJW (as Pig likes to say) or a white knight (Hyde's preferred insult), I'm not using the word stereotype with any negative implications. A stereotype is just a generalisation about a group of people, true or not. It's just about how people perceive other people. So, to answer the OP, biological differences in sex affects how people perceive the different genders.
Last edited by Ele; Feb 1, 2015 at 09:05 AM.