It happened [one morning] [20 years ago]. A British scientist Alec Jeffrey came across DNA fingerprinting: He identified the patterns of genetic material (that are unique to almost every individual). His discovery changed everything from the way (we do criminal investigations) to the way (we decide family law). But the professor of genetics at the University of Leicester, <UK>, is still surprised, and [a bit] worried, by the power of the technology (he released upon the world).

The patterns within DNA are unique to each individual, except identical twins, (who share the same pattern). The ability to identify these patterns has been used to convict murderers and to clear people (who are [wrongly] accused). It is [also] used to identify the victims of war and settle disputes over {who is the father of a child}.

Jeffrey said | he and his colleagues made the discovery by accident || while tracking genetic variations. But, [within six months of the discovery], genetic fingerprinting had been used in an immigration case, to prove | that an African boy really was his parents' son. [In 1986], it was used for the first time in a British criminal case: It cleared one suspect after being accused of two murders and helped convict another man.

DNA testing is now very common. [In Britain], a national criminal database established in 1995 now contains 2.5 million DNA samples. The U.S. and Canada are developing similar systems. But there are fears about the stored DNA samples and | how they could be used to harm a person's privacy. That includes a person's medical history, racial origin or psychological profile. "There is the long-term risk (that people can get into these samples and start getting additional information about a person's paternity or risk of disease)," Jeffrey said.

DNA testing is not an unfailing proof of identity. [Still], it is considered a reasonably reliable system for determining the things (it is used for). Jeffrey estimates the probability of two individuals' DNA profiles matching in the most commonly used tests at one in a billion.

one morning 一天上午, 某日上午

come across... 偶然看见..., 偶然遇到..., 碰见, 发现

be unique to... 为...独有, 仅与...有关 从...到...

University of Leicester 莱斯特大学

a bit 一点

identical twin 单卵性双细胞之一(性别相同,外貌相似)

be used to do sth (被)用来做某事

make a discovery 发现

by accident 意外地, 偶然地

genetic fingerprinting 基因指纹鉴定;遗传指纹法

for the first time 第一次, 首次,初次

be accused of... 被指控...

get into... 1) 进入 2) 对...产生兴趣 估计(收入、价值、数量等)在(某价位、区间)

one in a billion 十亿份之一