Dave, people aren't very symmetrical. For instance your Lymph system is very different left and right, not to mention organs and innervation.
As for breasts, most women on the planet have a larger left breast than right. One theory as to why is that babies over the ages have prefered the left breast because it is closer to the soothing sound of their mother's heart, leading to it's developement evolutionarily.
Now I want all you guys to go and conduct some field research to verify this factoid.
Hans Conser
