Your like of caffeine may be in your genes.

September 19, 2006 - Ever notice how flies never land on your morning of coffee, but do on your jelly covered toast? Well according to researchers at John Hopkins University, a single protein - Gr66a - may be responsible for this. According to the study, Drosapila flies with this specific protein removed also lost their sensitivity to caffeine' bitterness and migrated towards caffeine laced foods.  

The study which is published in the issue of Current Biology, ran tests on the flies’ brains to prove that the change originated in the flies’ taste bristles, the equivalent of human taste buds. Neurons attached to the bristle cells showed activity in response to caffeine only in the flies with a working receptor.

Interestingly, researchers said that Gr66a was not a “general sensor” for bitter compounds “but is required more specifically for the caffeine response”.

Links:

http://www.timesonline.co.uk/article/0,,2-2364027,00.html