But first, COFFEE. It's not a fault if you can't work before your cup, at least not yours. In fact, there are at least 2 scientific researches to agree with that.
In year 2014, a research based on 120,000 coffee drinkers and found 6 genetic markers that's that were related to their responsiveness to caffeine. (for detailed report of the research, please click here)
According to a scientific research released in the journal Scientific Reports in year 2016, scientists had identified a gene that relate to coffee consumption.
Researcher at the University of Edinburgh's Usher Institute of Population Health Sciences and Informatics authored the study. This research was done by comparing 1,200 people in Italy for their coffee consumption and genetic result to 1.731 people in Netherlands. Through the study, researcher found in both groups, the gene PDSS2 which thought to adjust the production of proteins that metabolize caffeine in the body of "heavy drinker" were tend to be less active or responsive, which result in metabolizing caffeine quicker and therefore they need more coffee as to gain the positive effects of caffeine. (for detailed report of the research, please click here)
However, some researchers disagreed with these studies as people tend to self control on their consumption of coffee based on the balance of the positive effect of caffeine such as mood. At the same time, the scale of study was relatively small when compared to the coffee drinker population and some similar study on same topic with different statistical models shows completely different results.
Apparently, we need more researches on this topic.