Experts of Edinburgh and Trieste Universities insist that people’s love of coffee might be genetic ,  reports the Kedem. The people who have certain changes in PDSS2 gene,  do not need to drink much coffee to feel the effects of the caffeine. A small cup is enough for them. PDSS2 gene affects the ability the organism to deplete  caffeine , as a result, it remains longer than usual . At the same time , people who do not have changes in PDSS2 gene,  deplete  the caffeine faster, and drink more coffee . These are results concluded by experts from Italy, after studying the DNA of 3,000 people living in the Netherlands.