Have you ever wondered how some people could make it through a whole day running on one cup of coffee while others could drink a gallon and still need a nap? Well I have since I'm one of those people who probably consume a typically dangerous amount of caffeine on a daily basis, and it turns out that it is actually linked to your genes. Researchers have found several variations of a gene that controls caffeine metabolism. Some people carry a variation where they metabolize caffeine more slowly than others who have a different variant. The slower your body metabolizes it, the less the person feels the need to drink it, while the faster a person's metabolism is, the more caffeine they can tolerate at a time. This is why some people feel jittery or anxious after one cup as opposed to others who just feel more happy and energized. In addition to a link to caffeine metabolism, scientists also noted that those same genes also coded for how the body metabolizes other drugs in the body, like nicotine. This finding in the study could be very important to the future of medicine if they can link these genes controlling metabolism of other drugs as well, which could hopefully lead to new, more precise treatments of numerous diseases.