Our genes encode the layout of physical race tracks on which marbles of matter and information travel. Some people's bodies have a bunch of muscle tracks, so as they grow, their body benefits from the activity on those. They grow up to find it easier to gain muscle than other people.
For geniuses, I imagine that the brain is a perfectly laid out super highway. Any information that comes in gets to where it needs to go because there's signs and signals and traffic cops patrolling. If some piece of information can't find where to go, well, damned if we don't have a construction worker and a navigator jumping in the passenger seat with you to help out.
Ultimately, I think the brain is so plastic that each of us can one day decide to elect a new mayor to our body town. The new mayor can decide to tear up roads and fix potholes etc. Yeah, it would have been great if we had founded the town with a plan and hadn't had that college riot but here we are. Time to pave some roads.