Tea or coffee? Your response may be determined before you’re even born. A new study published in the journal Scientific Reports, Understanding the Role of Bitter Taste Perception in Coffee, Tea, and Alcohol Consumption Through Mendelian Randomization,  explains how genetics affect sensitivity to bitterness in certain compounds, and results in a preference for either coffee or tea. Researchers in Australia, the United States, and the United Kingdom examined DNA from more than 430,000 individuals in the UK Biobank, a national resource of genetic data for medical research. The databank includes information on each person’s health, and self-reported behaviors, including coffee and tea consumption.

Perhaps surprisingly, the study found that people with a genetic sensitivity to bitterness in caffeine were more likely to have an increased coffee intake. Researches also discovered that sensitivity to bitterness in other chemical compounds (propylthiouracil and quinine) resulted in decreased coffee intake. For tea drinkers, the opposite is true. A decreased sensitivity to caffeine and increased sensitivity to propylthiouracil and quinine increases the likelihood that a person will have a higher tea intake.

The research is in almost direct opposition to researchers’ previous theories about bitter sensitivity and preference for beverages. It’s long been assumed that people with a higher sensitivity would avoid bitterness, because bitterness is an indicator of poison or rot. The new research indicates that drinkers may prefer a beverage because of its bitter taste.