Using data from other customers who consent to participate in research and customer’s genetics, 23andMe is able to report on the likelihood that you drink more or less than the average amount of caffeine. The role genetics play is based on a variant near two genes that play a role in how your body metabolizes caffeine. The gene CYP1A2 is involved with how your body breaks down the caffeine in coffee, and another gene, AHR, influences how CYP1A2 responds. Together these two genes affect how quickly the caffeine moves through your system.
There are other factors involved in why you may or may not drink more coffee or tea — or none at all — each morning than the average Joe. Culture certainly plays a role.