是的，你可能天生就爱喝咖啡！

Most of us can't get going without a morning cup of Joe. But some people need two or three cups before they feel alert. What accounts for the difference? Genetics play a crucial role in the way you process coffee.

我们中的大多数人在早晨都需要一杯咖啡来提神，但是有些人却需要更多(两到三杯)才会感到清醒。是什么原因导致了这种差异呢?答案可能隐藏在你体内。最近的研究表示，是基因使得每个人对咖啡的反应有所差异。

A June 2018 report authored for the Institute for Scientific Information on Coffee by physician J.W. Langer found most coffee drinkers fall into one of three major groups, depending on the way they metabolize caffeine, the stimulant found in coffee.

今年6月，兰格博士为咖啡科学信息研究所撰写的一份报告表示：根据人们代谢咖啡因(咖啡中的兴奋剂)的方式，大多数咖啡饮者可以被分为三大类。

Caffeine doesn't stay in our bodies but is metabolized (broken down) in the liver. The main enzyme in the liver that does this is called CYP1A2. Different people have different versions of this enzyme depending on their genetic makeup and the type you have determines how quickly or slowly caffeine remains in your liver. This genetic variability also affects the binding of caffeine to your brain receptors, which influences how alert or tired you feel after, say, one cup of coffee.

咖啡因被我们喝进去后，不会停留在我们的身体里，而是在肝脏中被代谢。肝脏中用于代谢咖啡因的主要酶被称为CYP1A2，每个人的这种酶都有所差异，这取决于你的基因组成。而这种遗传变异性也会影响咖啡因与大脑受体的结合，这便影响了你在喝完一杯咖啡后会有什么样的反应。

Here's how Dr. Langer broke down the three groups:
兰格博士将人们大致分成以下三种：

High Sensitivity: These folks get wired from small amounts of caffeine and can have trouble sleeping because of this. Their livers metabolize caffeine at a snail’s pace, while their central nervous systems (comprising brain and spinal cord) go into high alert. Only a few people fall into this category.

对咖啡因高度敏感：这些人只需要少量的咖啡因就会兴奋，并因此而难以入睡。他们的肝脏几乎在以蜗牛的速度代谢咖啡因，而他们的中枢神经系统只需要一点咖啡因就会进入高度警戒状态。一般来说，只有少数人属于这一类。

Regular Sensitivity: People in this category can down two to five cups a day and still sleep just fine — as long as they skip an evening dose.

对咖啡因常规敏感：这类人每天喝两到三杯咖啡也依然可以睡得很好，只要他们不在晚上引用咖啡。

Low Sensitivity: These coffee drinkers metabolize caffeine very quickly. They can have several cups of coffee, and even a night-cap cup without feeling jittery or having their sleep disturbed. But to get the jolt of alertness from caffeine that people in the other two categories do, they have to drink a lot more coffee. (Health professionals caution against drinking more than five cups a day.)

对咖啡因低度敏感：这类人能够很快地代谢咖啡因。他们每天都可以喝好几杯咖啡，甚至在夜间饮用也不会影响到他们的睡眠。为了让咖啡因使他们保持清醒，他们不得不喝更多的咖啡(健康专家提示最好不要超过5杯)。

"It's common for people to ask their doctor questions such as why they are kept awake by one cup of coffee, while their partner easily falls asleep after five cups," said Langer in a press statement. "The answer is that we are all unique coffee drinkers. Our genetic make-up programmes our reaction to caffeine, just as it programmes our hair colour and eye colour."

兰格在一份新闻声明中表示：“人们常常会问我，为什么一杯咖啡能让他们保持清醒，而他们的伴侣在喝完五杯咖啡后仍然很容易睡着。答案就隐藏在我们的基因里，是我们的基因决定了我们对咖啡因的反应，就像它影响我们眼睛的颜色一样”。