2021考研英語長難句復習（二十五）

　　

　　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.

　　【長難句分析圖解】

　　篇章超精讀

　?、貰ut 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.

　?、贖e 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.

　?、躎his 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.

　　參考譯文

　?、俚怯行┯^察者對此表示懷疑。Troy Duster 是紐約大學的一位社會學家，他認為“那些聲稱他們在進行先祖測試的人其實在吹噓一種虛假的準確率”。

　　②他指出，一個人有著很多的祖先——往回追溯幾百年，祖先數(shù)量就以百計。

　?、廴欢?，大多數(shù)的祖先測試都只考慮一個單一的族系，要么是從父親身上得來的男性攜帶的 Y 染色體，要么就是僅從母親身上遺傳的線粒體 DNA。

　?、苓@種 DNA 只能揭示 1~2 位祖先信息，而僅 3 代以前，一個人就有六位曾祖，而四代以前就有另外 14 位高祖。