模拟题：雅思阅读经典的模拟题_雅思英语真题

模拟题：雅思阅读经典的模拟题

　　Research has shown that there is genetic or inherited element to handedness. But while left-handedness tends to run in families， neither left nor right handers will automatically produce off-spring with the same handedness； in fact about 6 per cent of children with two right-handed parents will be left-handed. However， among two left-handed parents， perhaps 40 per cent of the children will also be left-handed. With one right and one left-handed parent， 15 to 20 per cent of the offspring will be lefthanded. Even among identical twins who have exactly the same genes， one in six pairs will differ in their handedness.

　　What then makes people left-handed if it is not simply genetic？ Other factors must be at work and researchers have turned to the brain for clues. In the 1860s the French surgeon and anthropologist， Dr Paul Broca， made the remarkable finding that patients who had lost their powers of speech as a result of a stroke （a blood clot in the brain） had paralysis of the right half of their body. He noted that since the left hemisphere of the brain controls the right half of the body， and vice versa， the brain damage must have been in the brains left hemisphere， Psychologists now believe that among right handed people， probably 95 per cent have their language centre in the left hemisphere， while 5 per cent have right-sided language， Left-handers， however，do not show the reverse pattern but instead a majority also Some 30 per cent have right hemisphere language.