Human babies seem to know how to swim. They also have other innate behavior such as sucking thumbs, nipples, etc. and having a tight grip (to hold on to the mother). It seems that humans are not the only animals that have this character. Deer, for example, also have an innate fear of certain predators.
I assume that this is stored in DNA so that the brain is formed in such a way that these memories always exist from the beginning. But how does that work? How are certain neurons born with dendrites and axons in states of depression or high activity and not all others?