A research team at Emory University of Medicine has produced laboratory evidence
of genetic memory in mammals. It's long been suspected that key survival traits can be transmitted genetically, (as opposed to social instruction), but there's been no evidence of the mechanism until now.
For example, why are humans inherently afraid of the dark? The obvious answer is that lions and other predators -- monsters, if you will -- lurk in the dark. They can see and stalk us, but we can't see them. That survival trait, fear of the dark, was genetically ingrained into the entire species at some point. But how? These guys think they've figured it out.
Essentially, if a sensory input combined with experience creates a strong enough emotion such as fear, the brain will send signals to the DNA in reproductive cells that alter it accordingly -- i.e., your mind "seeds" a strong reaction to that specific set of sensory inputs into your genetic code. It's not that your brain is telling you "hide from the lions!" when the lights go out. It's more subtle than that. The aversion is a second-order effect of generations of Ug watching Oog getting caught and eaten by lions at night. Thus Dark = Bad.
Of course, it's all much more complicated than that in reality. But the principle is valid. And if it proves out, it would be one more step towards a detailed understanding of the human psyche.