美国国家公共电台 NPR My Grandmother Was Italian. Why Aren't My Genes Italian?

 

RACHEL MARTIN, HOST:

Chances are you have seen an ad for a test to find out about your ancestry¹. Maybe you got a kit² for Christmas, and now you're waiting for your results. So what do you need to know when you open these results? Health editor Gisele Grayson and her mother help us explain.

GISELE GRAYSON, BYLINE³: History professors never really retire.

CARMEN GRAYSON: Are you clicking view your reports, Gisele?

G. GRAYSON: All right. All right. View my report.

I'm with Carmen Grayson, my mother, who taught at Hampton University for 25 years.

C. GRAYSON: World history, military history, American history, Greece and Rome history (laughter). Do you want me to stop?

G. GRAYSON: We're opening genetic⁴ test results from a company called 23andMe. Mom recently became interested in what our genes⁵ could tell us about her family's migrations⁶ to Washington from Canada, from France and from Italy. We got some good information, and a puzzle. Last fall, we used a different company, Helix, that works with National Geographic⁷. Mom's results?

C. GRAYSON: Thirty-one percent from Italy and Southern Europe.

G. GRAYSON: Did you expect that?

C. GRAYSON: Definitely. Two grandparents, both born in Italy...

G. GRAYSON: And lived there as far as you can trace back. They gave birth to my mom's mom, Gisella D'Apollonia. But my Helix results had no Italian and Southern European category. Was I switched at birth?

C. GRAYSON: You were born with a lot - a lot - of black, curly hair.

G. GRAYSON: So she was sure it was me in the hospital nursery. And we do kind of look alike. So we decided⁸ to get this second opinion from 23andMe.

C. GRAYSON: My top category is Italian, 11 percent. Do you have any Italian?

G. GRAYSON: I have 1.6 percent Italian.

C. GRAYSON: There you go.

G. GRAYSON: (Laughter). All right.

C. GRAYSON: My daughter.

G. GRAYSON: But, really, how could I have an Italian grandmother and little to no Italian in my results? We put the question to geneticist Aravinda Chakravarti at Johns Hopkins.

ARAVINDA CHAKRAVARTI: That's surprising, but it may still be within the limits of error that these methods have.

G. GRAYSON: The science is good, he says, but the ways the companies analyze⁹ genes leave room for interpretation¹⁰.

CHAKRAVARTI: They would be most accurate at the level of continental¹¹ origins, and as you go to higher and higher resolution, they would become less and less accurate.

G. GRAYSON: As in my case. The results got me to Europe, just not Italy. A few things are at play in this ancestry analysis. First is our actual genetic material. The rule is you get 50 percent of your DNA¹² from each parent. But Elissa Levin, with the company Helix, says a process called recombination means each egg and each sperm¹³ carries a different mix of your parents' genes.

ELISSA LEVIN: When we talk about the 50 percent that gets inherited from Mom, there is a chance that you have a recombination that just gave you more of the Northwest European part rather than the Italian part of of your mom's ancestry DNA.

G. GRAYSON: Then she says that companies compare your DNA to samples they have from people around the world who have lived in a certain area for generations.

LEVIN: What are the specific markers? What are the specific segments of DNA that we're looking at that enable us to identify, you know, those people are from this part of Northern Europe, or Southern Europe or Southeast Asia?

G. GRAYSON: And as the companies get more samples, they'll get more accurate. Also humans have migrated and mingled¹⁴ for tens of thousands of years, and most people have a DNA mix. So - says Robin¹⁵ Smith, with 23andMe - a computer algorithm does some sophisticated guesswork.

ROBIN SMITH: Let's say a piece of your DNA looks most like British and Irish, but it also looks a little bit like French, German. Well, based on some statistical¹⁶ measures, you know, we would decide whether to call that as British, Irish or French, German. Or maybe we'd go up one level and we call it North Western European.

G. GRAYSON: Could that explain my case?

SMITH: It was a little surprising to me, yeah. But, you know, in looking at, you know, the fact that you had some Southern European and the fact that you had some French, German, the picture became a little bit clearer to me.

G. GRAYSON: So for now my Italian grandmother doesn't show up in these tests. No matter, all the researchers say, let the results add to your life story. The DNA is just a piece of what makes you you. Gisele Grayson, NPR News.

MARTIN: And just a note - the company 23andMe mentioned in this story is an NPR funder.

1 ancestry   

n.祖先，家世

参考例句：

• Their ancestry settled the land in 1856.他们的祖辈1856年在这块土地上定居下来。
• He is an American of French ancestry.他是法国血统的美国人。

2 kit   

n.用具包，成套工具；随身携带物

参考例句：

• The kit consisted of about twenty cosmetic items.整套工具包括大约20种化妆用品。
• The captain wants to inspect your kit.船长想检查你的行装。

3 byline   

n.署名；v.署名

参考例句：

• His byline was absent as well.他的署名也不见了。
• We wish to thank the author of this article which carries no byline.我们要感谢这篇文章的那位没有署名的作者。

4 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

5 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

6 migrations   

n.迁移，移居( migration的名词复数 )

参考例句：

• It foundered during the turmoils accompanying the Great Migrations. 它在随着民族大迁徙而出现的混乱中崩溃。 来自辞典例句
• Birds also have built-in timepieces which send them off on fall and spring migrations. 鸟类也有天生的时间感应器指导它们秋春迁移。 来自互联网

7 geographic   

adj.地理学的，地理的

参考例句：

• The city's success owes much to its geographic position. 这座城市的成功很大程度上归功于它的地理位置。 来自《简明英汉词典》
• Environmental problems pay no heed to these geographic lines. 环境问题并不理会这些地理界限。 来自英汉非文学 - 环境法 - 环境法

8 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

9 analyze   

vt.分析，解析 (=analyse)

参考例句：

• We should analyze the cause and effect of this event.我们应该分析这场事变的因果。
• The teacher tried to analyze the cause of our failure.老师设法分析我们失败的原因。

10 interpretation   

n.解释，说明，描述；艺术处理

参考例句：

• His statement admits of one interpretation only.他的话只有一种解释。
• Analysis and interpretation is a very personal thing.分析与说明是个很主观的事情。

11 continental   

adj.大陆的，大陆性的，欧洲大陆的

参考例句：

• A continental climate is different from an insular one.大陆性气候不同于岛屿气候。
• The most ancient parts of the continental crust are 4000 million years old.大陆地壳最古老的部分有40亿年历史。

12 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

13 sperm   

n.精子，精液

参考例句：

• Only one sperm fertilises an egg.只有一个精子使卵子受精。
• In human reproduction,one female egg is usually fertilized by one sperm.在人体生殖过程中，一个精子使一个卵子受精。

14 mingled   

混合，混入( mingle的过去式和过去分词 )； 混进，与…交往[联系]

参考例句：

• The sounds of laughter and singing mingled in the evening air. 笑声和歌声交织在夜空中。
• The man and the woman mingled as everyone started to relax. 当大家开始放松的时候，这一男一女就开始交往了。

15 robin   

n.知更鸟，红襟鸟

参考例句：

• The robin is the messenger of spring.知更鸟是报春的使者。
• We knew spring was coming as we had seen a robin.我们看见了一只知更鸟，知道春天要到了。

16 statistical   

adj.统计的，统计学的

参考例句：

• He showed the price fluctuations in a statistical table.他用统计表显示价格的波动。
• They're making detailed statistical analysis.他们正在做具体的统计分析。