基因决定友谊 好友缘分是天注定？

　　Research has shown that people tend to become friends with people similar to themselves. But now friendship is in our genes, scientists believe, with two friends sharing the some of the same DNA, while in other cases, friends have different versions of the same gene。

　　To find out if that theory holds water, James Fowler, a professor of medical genetics at the University of California and his colleague Nicholas Christakis at the Havard University culled data from two large studies which collected genetic information as well as data on friendship, marriage and other relationships. Then they tested the friendship pairs from the studies for six genes known to influence human behavior。

　　Of the six genes tested, the first involved a gene called DRD2 which affects how much pleasure we get from alcohol and cigarettes and other addictive substances. The study revealed that people with a version of the gene tend to befriend others with the same version. The opposite relationship was found for a gene called CYP2A6. Those with a version of the gene linked to having an "open" personality, gravitated to people with a different version of the gene, according to the Harvard University。

　　Christakis said that reasons for us being drawn to those who are genetically similar to ourselves include us being thrown together with people with similar interests in sports clubs or at university. But we may also actively seek out those who are like us – even if we are unaware of the underlying genetics. For instance, thin people may stick together, unaware that each member of the group lacks genes that make it easy for others to pile on the pounds. In terms of opposite attracting, we may hunt out people whose personalities complement our own. Extraverts may meet their quieter pals through work。