When it comes to males and females, research has shown that females have better advantage at multitasking in general. Although this is true, it is also my experience that the advantage is not that great, and in general, if anyone tries to multitask, usually one, two, or even all of the tasks are worse off than if we were to concentrate on them one at a time.
No one can truly consciously multitask, that is, to run two tasks or more at the very same time that requires conscious effort. Even for those who are pretty good at it, what is most likely happening is the alternating between the tasks very quickly such that it seems like multitasking.
All single core processors can't truly multitask. You may be on IM, surfing the internet, listening to music, while typing out a document, and the computer does it all simultaneously. Despite this, it is not truly multitasking. What really is happening is that while running some parts of a program, it may require to call information from or pass information to the harddisk or the RAM or maybe the graphics card or sound card. Since these usually are slower than the processor itself, the processor has some "free time" while waiting for the other components to process and give back information. The processor then uses this "free time" to run your other programs and etc. This happens many times each second, and thus, it looks like the computer is multitasking.
However, as we know it, while the conscious mind is works similar to a single processor computer, we have the unconscious mind as well, and it is another processor, I daresay, much stronger than the conscious.
While doing any task, or even just staying alive, the unconscious part of our brains control our bodily functions that keep us alive. We thus are able to do tasks like talk while living. This is, true multitasking, but as you can see, it requires two seperate processors that are linked to each other, but nevertheless, not the same.
You also see that for dual processor computers, they run faster than single processor computers when running two process intensive applications. However, if you try to run more processes/programs than 2, the old method still has to come into play, and the computer will alternate between the tasks to "multitask", which is what we do when we try to talk on the phone while chatting on IM.