When left-handed mice live in right-handed worlds.

Many C57BL/6J inbred mice were tested for paw preference. In unbiased worlds, approximately 10 percent exhibited lateral preferences inconsistent with the world bias, and males were more strongly lateralized. Influences of world bias appear to be superimposed upon an already laterally dichotomized population. Initial left-right sense, it is posited, arises as an outcome of a seemingly random process.