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  3. It is a wise father that knows his own child, but today a man can boost his

It is a wise father that knows his own child, but today a man can boost his

游客2023-07-07  55
问题     It is a wise father that knows his own child, but today a man can boost his paternal(fatherly)wisdom — or at least confirm that he’s the kid’s dad. All he needs to do is shell out $30 for paternity testing kit(PTK)at his local drugstore — and another $120 to get the results.
    More than 60,000 people have purchased the PTKs since they first become available without prescriptions last years, according to Doug Fogg, chief operating officer of Identigene, which makes the over-the-counter kits. More than two dozen companies sell DNA tests directly to the public, ranging in price from a few hundred dollars to more than $2,500.
    Among the most popular: paternity and kinship testing, which adopted children can use to find their biological relatives and families can use to track down kids put up for adoption, DNA testing is also the latest rage among passionate genealogists — and supports businesses that offer to search for a family’s geographic roots.
    Most tests require collecting cells by webbing saliva(唾液)in the mouth and sending it to the company for testing. All tests require a potential candidate with whom to compare DNA.
    But 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. He notes that each individual has many ancestors — numbering in the hundreds just a few centuries back. Yet most ancestry testing only considers a single lineage(世系), either the Y chromosome(染色体)inherited through men in a father’s line or mitochondrial(线粒体)DNA, which is passed down only from mothers. This 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.
    Critics also argue that commercial genetic testing is only as good as the reference collections to which a sample is compared. Databases used by some companies don’t rely on data collected systematically but rather lump together information from different research projects. This means that a DNA database may have a lot of data from some regions and not others, so a person’s test results may differ depending on the company that processes the results. [br] What is the author mainly discussing in the passage?
选项 A、Fors and Againsts of DNA testing.
B、DNA testing and its problems.
C、DNA testing outside the lab.
D、Lies behind DNA testing.
答案 B
解析 根据题干将本题出处定位于文章四个段落的中心句。文章前两段主要介绍PTK这种检测，父子关系的方法，引出基因检测方法；第3、4段说明基因检测的主要用途及简单原理；最后两段对基因检测的准确性提出质疑。显然，文章主要介绍的是基因检测及其存在的问题，B)概括完整，故为答案。文中并未说明支持基因检测的人的观点，故A)不符合原文。C)“实验室外的基因检测”偏离主题。D)“基因检测背后的谎言”只是文章内容的一小部分，不能概括主题。
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