Given that the rostral (head) end of the neural tube literally bends inward (cephalic flexure) as it grows into the enclosed space of the head to later become the brain, and that the tip is also attached to a clump of cells that will become the heart (cardiac anlage) which is also migrating downwards with the tip of the neural tube and to the left side of the chest, it is altogether unsurprising that the brain should be slightly pulled to the left.