Well... in JupiterMoon's defense, the word is overloaded (in the C++ sense). We use "him" for "male", and also (historically) for "person of unspecified/unknown gender".

Now, we're more using "her" for "person of unspecified/unknown gender", but the problem remains: We've got three states (male, female, and unknown/unspecified), and only two words (him and her). No matter what, there's going to be this kind of problem, until we come up with a third word. (People have suggested "they" or "them", but I don't like it because of singular/plural issues.)