Press play on your earliest happy memory. Your presence is transported to the past, where you feel temperature change, see younger versions of family members interact and even smell the succulent aromas around you. A vivid experience drenches the senses and embosses an indelible memory on the brain's surface. Why do some remember (and even dream) in exquisite sensory detail, while others watch only monochromatic versions of their past? The answer lies in their genes.