Charlie Chasen and Michael Malone met in Atlanta in 1997, when Mr. Malone served as a guest singer in Mr. Chasen’s band. They quickly became friends, but they didn’t notice what other people around them did: The two men could pass for twins.

查理·蔡森和迈克尔·马龙于1997年在亚特兰大相识，当时马龙在蔡森的乐队中担任客座歌手。他们很快成为了朋友，但他们没有注意到周围的人是如何看待他们的：这两个男人看上去完全可以是双胞胎。

Mr. Malone and Mr. Chasen are doppelgängers. They look strikingly similar, but they are not related. Their immediate ancestors aren’t even from the same parts of the world; Mr. Chasen’s forebears hailed from Lithuania and Scotland, while Mr. Malone’s parents are from the Dominican Republic and the Bahamas.

马龙和蔡森是所谓的“二重身”——他们的相貌惊人地相似，却没有血缘关系。他们的直系祖先甚至不是来自世界的同一个地方；蔡森的祖先来自立陶宛和苏格兰，马龙的父母来自多米尼加共和国和巴哈马群岛。

The two friends, along with hundreds of other unrelated look-alikes, participated in a photography project by François Brunelle, a Canadian artist. The picture series, “I’m not a look-alike!,” was inspired by Mr. Brunelle’s discovery of his own look-alike, the English actor Rowan Atkinson.

这两个朋友，以及其他数百名没有亲戚关系的相貌相似者参加了加拿大艺术家弗朗索瓦·布鲁内尔的一个摄影计划。这个作品系列名为“我不是高仿！”，灵感来自布鲁内尔发现了他自己的“高仿版”——英国演员罗温·阿特金森。

The project has been a hit on social media and other parts of the internet, but it’s also drawn the attention of scientists who study genetic relationships. Dr. Manel Esteller, a researcher at the Josep Carreras Leukaemia Research Institute in Barcelona, Spain, had previously studied the physical differences between identical twins, and he wanted to examine the reverse: people who look alike but aren’t related. “What’s the explanation for these people?” he wondered.

该计划在社交媒体和互联网的一些地方引起了轰动，但也吸引了研究基因关系的科学家注意。西班牙巴塞罗那何塞·卡雷拉斯白血病研究所的研究员曼内尔·埃斯特勒博士此前曾研究过同卵双胞胎之间的生理差异，他想研究的是相反的情况：长得很像但没有血缘关系的人。“该怎么解释这些人？”他想。
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In a study published Tuesday in the journal Cell Reports, Dr. Esteller and his team recruited 32 pairs of look-alikes from Mr. Brunelle’s photographs to take DNA tests and complete questionnaires about their lifestyles. The researchers used facial recognition software to quantify the similarities between the participants’ faces. Sixteen of those 32 pairs achieved similar overall scores to identical twins analyzed by the same software. The researchers then compared the DNA of these 16 pairs of doppelgängers to see if their DNA was as similar as their faces.

周二发表在《细胞报告》(Cell Reports)期刊上的一项研究中，埃斯特勒和他的团队从布鲁内尔的摄影活动中招募了32对长得很像的人进行DNA测试，并完成有关他们生活方式的问卷调查。研究人员使用面部识别软件来量化参与者面部的相似性。在这32对参与者中，有16对的总体得分与使用同一软件分析的同卵双胞胎相似。然后，研究人员比较了这16对二重身的DNA，研究他们的DNA是否和他们的外貌一样相似。
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Dr. Esteller found that the 16 pairs who were “true” look-alikes shared significantly more of their genes than the other 16 pairs that the software deemed less similar. “These people really look alike because they share important parts of the genome, or the DNA sequence,” he said. That people who look more alike have more genes in common “would seem like common sense, but never had been shown,” he added.

埃斯特勒发现，与软件认为不太相似的另外16对参与者相比，16对相貌“真正”相似的参与者的基因共享程度要高得多。“这些人看起来真的很像，因为他们拥有同样的基因组或DNA序列的重要部分，”他说。长得更像的人拥有更多的共同基因，“这似乎是常识，但从来没有被证明过，”他补充说。

However, DNA alone doesn’t tell the whole story of our makeup. Our lived experiences, and those of our ancestors, influence which of our genes are switched on or off — what scientists call our epigenomes. And our microbiome, our microscopic co-pilot made up of bacteria, fungi and viruses, is further influenced by our environment. Dr. Esteller found that while the doppelgängers’ genomes were similar, their epigenomes and microbiomes were different. “Genetics put them together, and epigenetics and microbiome pulls them apart,” he said.

然而，DNA本身并不能说明我们身体的全部情况。我们的生活经历，以及我们祖先的生活经历，会影响我们基因的开启或关闭——科学家称之为我们的表观基因组。我们身体中的的微生物组——由细菌、真菌和病毒组成的微观副驾驶——进一步受到环境的影响。埃斯特勒发现，虽然二重身的基因组很相似，但他们的表观基因组和微生物组却不同。“遗传学把他们放在一起，表观遗传学和微生物组则把他们分开，”他说。

This discrepancy tells us that the pairs’ similar appearances have more to do with their DNA than with the environments they grew up in. That surprised Dr. Esteller, who had expected to see a bigger environmental influence.

这种差异告诉我们，外表相似的两人更多与其DNA有关，而不是与成长环境有关。这让埃斯特勒感到惊讶，他原本预计会看到更大的环境影响。

Because the doppelgängers’ appearances are more attributable to shared genes than shared life experiences, that means that, to some extent, their similarities are just the luck of the draw, spurred on by population growth. There are, after all, only so many ways to build a face.

因为二重身的长相更多要归因于共同的基因而不是共同的人生经历，这意味着在某种程度上，他们的相似只是人口增长作用下的偶然事件。毕竟，长相的生成模式只有那么多。

“Now there are so many people in the world that the system is repeating itself,” Dr. Esteller said. It’s not unreasonable to assume that you, too, might have a look-alike out there.

“现在世界上人太多了，这个系统正在自我重复，”埃斯特勒说。某个地方也可能会有跟你长得很像的人，这种假设不是没有道理。

Dr. Esteller is hopeful that the study’s findings will help doctors diagnose illness in the future — if people have similar enough genes to look alike, they might share predilections for diseases too.

埃斯特勒希望该研究结果能在未来有助于医生诊断疾病——如果人们的基因相似到长相也相似，那或许他们的易患疾病也是相同的。

“There seems to be something pretty strong in terms of genetics that is making two individuals who look alike also having genome-wide similar profiles,” said Olivier Elemento, the director of the Englander Institute for Precision Medicine at Weill Cornell Medicine in New York, who was not involved with the study. Discrepancies between DNA’s predictions and people’s actual appearances might alx doctors to problems, he said.

“两个长相相似的个体也拥有相似的全基因组图谱，这可能与遗传学有很大关系，”纽约威尔康奈尔医学院英格兰德精准医学研究所所长奥利维尔·埃莱门托说，他并未参与这项研究。他表示，如果DNA预测的结果和人的实际外貌不一致，这就可能值得医生的警惕。

Dr. Esteller also suggested that there could be lixs between facial features and behavioral patterns, and that the study’s findings might one day aid forensic science by providing a glimpse of the faces of criminal suspects known only from DNA samples. However, Daphne Martschenko, a postdoctoral researcher at the Stanford Center for Biomedical Ethics who was not involved with the study, urged caution in applying its findings to forensics.

埃斯特勒还表示，面部特征和行为模式之间可能存在联系，该研究结果或许也能在未来助力司法科学研究，仅靠DNA样本就能一窥犯罪嫌疑人的长相。并未参与这项研究的斯坦福大学生物医学伦理中心博士后研究员达芙妮·马尔琴科表示，此研究结果在司法鉴定中的应用需要谨慎。

“We’ve already seen plenty of examples of how existing facial algorithms have been used to reinforce existing racial bias in things like housing and job hiring and criminal profiling,” Dr. Martschenko said, adding that the study “raises a lot of important ethical considerations.”

“我们已经看到有大量案例表明，在住房、就业和犯罪分析等问题上，现有面部算法是如何被用于强化现存种族偏见的，”马尔琴科表示，她还说，该研究“引发了许多重要的伦理考量”。

Despite the potential pitfalls of lixing people’s appearances with their DNA or their behavior, Mr. Malone and Mr. Chasen said the look-alike project, and the knowledge that we all might have a secret twin out there, was a means of bringing people together. The two have remained friends for 25 years; when Mr. Chasen got married last week, Mr. Malone was the first person he called. While not everyone with similar DNA shares such a bond, Mr. Malone said that he saw Mr. Brunelle’s photography project as “another way to connect all of us in the human race.”

尽管将人的长相与其DNA或行为进行关联存在隐患，但马龙和蔡森表示，这个外貌雷同计划，以及知道每个人可能都有一个未知的双胞胎兄弟姐妹这一点可以拉近人们的距离。他们两人的友谊已经持续了25年；蔡森上周结婚时，马龙是他第一个去电通知的对象。虽然不是所有DNA相似的人都能有这样的纽带，但马龙说，他认为布鲁内尔的摄影计划是“又一种将人类所有成员连结到一起的办法”。