I don't know nor does science but are you suggesting there is a gene which when switched on and off makes a fetus prefer to turn its head to the left or right? Why would such a gene exist?
The fact that the right and left hemispheres undertake different tasks and therefore left and right handed people develop subtly different skill sets is not being questioned. The brain structure is the same in everyone, the wiring on the other hand is unique and is developed on the behavior of learning.So - not all our houses are the same?