A study has found new clues into why some people become left-handed and others become right-handed. Researchers have found that the trait, shared by about 10 per cent of people, could have something to do with our genes. The findings, published in the journal Nature Communications, identified rare variants (变体) of a gene involved in controlling the shape of cells and found them to be 2.7 times more common in left-handed people. 

While the genetic (基因的) variants were found in only a tiny amount of left-handed people, about 0.1 per cent, the researchers said the study showed the gene, called TUBB4B, could lead to someone using either the left or right side of their brains for learning language. Those who mostly use the left side of the brain when learning language tend to write with their right hand, while those who mostly use the right side of their brain become left-handed.

The study looked at the genetic data of more than 350,000 middle-aged or older adults from Britain. About 11 per cent were left-handed.

The study could throw some light on the role of genes leading to right or left handedness, one of the lead authors, Clyde Francks said. But despite the genetic link found in the study, for most people, whether or not they became left-handed could purely be down to chance, he added.

Over the centuries, many cultures have looked down upon left-handedness and tried to force them to become right-handed. In English, the word “right” also means “correct” or “proper.” The word “sinister” came from a Latin word meaning “on the left side.” Even today, the Italian word for “left” is “sinistra”. And a “left-handed compliment” means an insult covered up as praise.

The number of left-handed people varies across the world. There have been found to be fewer left-handed people in Africa, Asia and the Middle East compared to Europe and North America, Francks said. He said in many countries, naturally left-handed kids are still made to use their right hand to write and draw.

1.What can we know about the study?

A The variants were found in lots of left-handed people.

B It’s more common to see the variants in left-handed people.

C Not all its participants come from the UK.

D It found about 10% participants are left-handed.

解析：选B。B细节理解题。根据第一段的“found them to be 2.7 times more common in left-handed people”可知，这种基因变异在左撇子人群中更常见，是右撇子人群的2.7倍。故选B。

2.What’s Francks’s attitude to the result?

A It’s not meaningless.

B It’s not useless.

C It’s not universal.

D It’s not obvious.

解析：选C。C推理判断题。根据倒数第三段中的“could throw some light on the role of genes leading to right or left handedness ... But ... for most people, whether or not they became left-handed could purely be down to chance”可知，弗兰克斯认为，这项研究可能会在“基因导致左撇子和右撇子”方面起一定作用，但是对大多数人来说，是否成为左撇子全靠运气。由此可知，弗兰克斯认为他们的研究的结果不适用于大众，只适用于部分人群。故选C。

3.“Sinister” is most probably a word _______.

A that expresses praise

B that means caring nothing

C without any strong feeling

D that shows a critical attitude

解析：选D。D推理判断题。根据划线词所在段的段首句“many cultures have looked down upon left-handedness”可知，该段主要讲的是许多文化都蔑视左撇子，然后后面具体举了几个例子，由此可推知，此处sinister应该是一个带贬义的词。故选D。

4.Which country may have the most left-handed people?

A Thailand.

B France.

C South Korea.

D Turkey.

解析：选B。B推理判断题。根据最后一段中的“There have been found to be fewer left-handed people in Africa, Asia and the Middle East compared to Europe and North America”可知，与欧洲和北美洲相比，非洲、亚洲和中东的左撇子较少。结合选项可知，只有法国属于欧洲，那里的左撇子可能最多。故选B。