2021考研英語(yǔ)長(zhǎng)難句復(fù)習(xí)（二十四）

　　

　　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(zhǎng)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.

　?、踄et 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(duì)此表示懷疑。Troy Duster 是紐約大學(xué)的一位社會(huì)學(xué)家，他認(rèn)為“那些聲稱他們?cè)谶M(jìn)行先祖測(cè)試的人其實(shí)在吹噓一種虛假的準(zhǔn)確率”。

　?、谒赋觯粋€(gè)人有著很多的祖先——往回追溯幾百年，祖先數(shù)量就以百計(jì)。

　?、廴欢?，大多數(shù)的祖先測(cè)試都只考慮一個(gè)單一的族系，要么是從父親身上得來(lái)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(gè)人就有六位曾祖，而四代以前就有另外 14 位高祖。