3. Even considering that some hardwiring is 'baseline', there is considerable variation among humans at birth, though we do not have the capacity yet to distinquish except between the most gross differences. Some of those significant differences have to do with sensitivity and functionality, and not with actual structure. Hormones, enzmes, other neurotransmitter chemicals, number, variation and sensitive of receptors, etc., etc. etc. Like the outer universe, infinite possibilities.

4. Experiences - stimuli - (among other factors) beginning before birth, and continuing throughout the life span, but especially during childhood, effect both the development of the brain structure itself, the hardwiring of brain 'circuits,' glandular output of hormones, the kinds of neural pathways or connections, the number of neural pathways and connections, the sensitivity to stimuli, the accessibility (superhighway or grown-over logging road) 'gates,' that influence which neural pathways get 'travelled' under what conditions, and so on.

5. In 4 above, remove 'experience' and insert the individual's initial hardwiring, hormones, et. al, based on genetics and in utero exposure to whatever crosses the placenta or travels through the umbilical cord. These influence the effect of the experiences-stimuli.

We do know that much, and not much else. Already, the possibilities, even within the individual brain, are infinite.