Biological and genetic causes
One of my pet peeves is the conflation of "biological" and "genetic"/"innate" when discussing the causes of behavior. As in the recent row over Summers' comments about women in science, people often refer to a "biological" explanation for X (e.g., scientific/mathematical ability) as opposed to a social-influences explanation, when what they really mean is a genetic or innate explanation.
In fact, all behavior has a "biological" explanation. This is true simply because the mind is the product of the brain. Any behavior you might be interested in has a cause somewhere in the brain, even if we can't yet figure out what it is. Similarly, any environmental influence that affects your behavior (learning, for example) necessarily has an effect on your brain because how else would the change in your behavior be implemented? Thus, if social pressures discourage women from entering science, this is because women encode these subtle societal biases as memory in their brains; and vice versa for men. It's simply nonsensical to describe "biological" explanations as being opposed to "social influences" explanations in any meaningful way.