Are you a social butterfly, or do you prefer being at the edge of a group of friends? Either way, your genes and evolution may play a major role, US researchers reported on Monday.

While it may come as no surprise that genes may help explain why some people have many friends and others have few, the researchers said, their findings go just a little farther than that.

你是爱好交际还是喜欢独来独往？美国研究人员于本周一报告称，不管你属于哪一类，你的基因及进化过程可能在这一问题上起着重要的作用。

研究人员称，用基因解释为什么有些人朋友众多而有些人却寡朋少友其实并不新鲜，不过他们的研究更深入一些。

"Some of the things we find are frankly bizarre," said Nicholas Christakis of Harvard University in Massachusetts, who helped conduct the study.

"We find that how interconnected your friends are depends on your genes. Some people have four friends who know each other and some people have four friends who don't know each other. Whether Dick and Harry know each other depends on Tom's genes," Christakis said in a telephone interview.

来自马萨诸塞州哈佛大学的尼古拉斯•克里斯塔奇斯协助开展该研究，他说：“我们发现的一些现象的确很奇怪。”

克里斯塔奇斯在一次电话采访中称：“我们发现一个人朋友之间的亲密程度取决于这个人的基因。有的人有四个朋友而且互相认识；而有的人有四个朋友，但他们却素不相识。也就是说，迪克和哈利是否互相认识是取决于汤姆的基因。”

Christakis and colleague James Fowler of the University of California San Diego are best known for their studies that show obesity, smoking and happiness spread in networks.

For this study, they and Christopher Dawes of UCSD used national data that compared more than 1,000 identical and fraternal twins. Because twins share an environment, these studies are good for showing the impact that genes have on various things, because identical twins share all their genes while fraternal twins share just half.

克里斯塔奇斯和他的同事、来自加利福尼亚大学圣地亚哥分校的詹姆斯•福勒此前以研究肥胖、吸烟以及快乐会在朋友之间传播而著名。

在这项研究中，他们和加利福尼亚大学圣地亚哥分校的克里斯托弗•道维斯使用了一项全国性数据，这项数据对1000多对同卵及异卵双胞胎的基因进行了对比。 由于双胞胎生活在同一个环境，而且同卵双胞胎的基因完全相同，而异卵双胞胎有一半的基因相同，所以这些研究有助于发现基因对人各个方面的影响。