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2021考研英语真题复习:长难句Day160

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【2009年阅读Text 2  第5段】

Yet most ancestry testing only considers a single lineage, either the Y chromosome inherited through men in a father's line or mitochondrial DNA, which is passed down only from mothers.

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①But some observers are skeptical, "There is a kind of false precision being hawked by people claiming they are doing ancestry testing," says Trey Duster, a New York University sociologist.

②He notes that each individual has many ancestors-numbering in the hundreds just a few centuries back.

③Yet most ancestry testing only considers a single lineage, either the Y chromosome inherited through men in a father's line or mitochondrial DNA, which is passed down only from mothers.

④This DNA can reveal genetic information about only one or two ancestors, even though, for example, just three generations back people also have six other great-grandparents or, four generations back, 14 other great-great-grandparents.

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①但是有些观察者对此表示怀疑。Troy Duster 是纽约大学的一位社会学家，他认为“那些声称他们在进行先祖测试的人其实在吹嘘一种虚假的准确率”。

②他指出，一个人有着很多的祖先——往回追溯几百年，祖先数量就以百计。

③然而，大多数的祖先测试都只考虑一个单一的族系，要么是从父亲身上得来的男性携带的 Y 染色体，要么就是仅从母亲身上遗传的线粒体 DNA。

④这种 DNA 只能揭示 1~2 位祖先信息，而仅 3 代以前，一个人就有六位曾祖，而四代以前就有另外 14 位高祖。