What's Your Poison?

A study carried out in North America, limited to subjects presumably of 'European extraction' has attempted to determine whether genes influence one's preference for coffee or tea (https://www.theguardian.com/science/2018/nov/15/coffee-tea-drink-choice-study-linked-genes-how-we-perceive-bitterness). One must firstly note that the study relied on the subject's self-reports of their beverage drinking habitats but seemed to show that preference is linked to genes that alter perceptions of bitterness. In general, subjects with a gene that slightly increased the perception of bitterness of caffeine tended to drink more coffee. In addition, having genes that elevated the sensation of bitterness associated with quinine and propylthiourea produced, in contrast, small reductions in coffee drinking. The opposite seemed to be true for subjects with a preference for tea drinking. The findings might well be limited to subjects from this limited background (and Geography) and one might ask whether sugar and cream additions alter preferences.