The genetics behind taste – kitchen science

Cilantro. Most people either love it, or they hate it. I grew up with a mother who disliked it so much that she would often tell the waitstaff in restaurants that she was allergic to it, just so that it wouldn’t accidentally end up as a garnish on her plate. Sadly, I inherited her aversion to the herb…and not just because I was influenced by her bias against it. As much as I adore Mexican food, you would think that I would look forward to a taco topped with a heaping mound of salsa fresca. But sadly for me, the second I take a bite of any cilantro laced meal, I feel as if my mouth has been washed out with soap. Yes, soap.

While I can’t blame my mom for influencing my thoughts about cilantro, I can blame her for what happens in my mouth. You see, the aversion to the taste and smell of cilantro (and several other flavors) is genetic. Each of us inherits a copy of every trait (or gene) from both of our parents, and the way that we express that trait is dependent on which combination of DNA resulted at the time of our conception.

In my high school biology class today, we experienced the genetics of taste firsthand, and visually represented our characteristics on a tree of genetic traits (from the University of Utah). Our tongues are coated in taste buds, each of which is filled with specialized cells that can detect a variety of flavors. Some of these cells are specially adapted to recognize bitter flavors, presumably with the evolutionary advantage of telling us if we eat a potentially dangerous plant. The cells send a signal through the nervous system to tell the brain how to respond. In some cases, if the flavor is too strong, you may have an involuntary gag response or you may automatically spit out the food. Of course, it is worth mentioning that you can influence your taste buds – either by frying them smoking cigarettes or by practice eating foods you don’t like.

tree of genetic traits

Quite by accident, a scientist came across a chemical compound called PTC (phenylthiocarbamide) that was bitter to a colleague but not to himself. After further research, they determined that certain people carried the “tasting” trait, while others did not. Science supply companies now sell small tubes filled with strips of paper impregnated with PTC for science classes studying genetics. Much to the chagrin of my students, we set out to determine who were tasters and who were not. The results were quite dramatic, with some students looking around, confused, at their classmates who were cringing, pawing at their tongues and running to the sinks to rinse the bitter flavor out of their mouths.

student tasting PTC paper

And who says that school is boring?

Are there any taste or smell aversions that run in your family?

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