2014广东省深圳市高考英语阅读理解冲刺课外自练（4）（答案）
阅读下列短文，从每题所给的A、B、C和D项中，选出最佳选项。
【深圳市2014高考英语综合能力测试题（4）】A
When you look at yourself in the mirror, do you ever wonder why you look the way you do? Do you also wonder what biological processes were at work to shape your face, which is as individual and unique as a fingerprint?
The answer is in a little piece of your DNA called a gene enhancer(增强片段),according to scientists at Berkeley Lab. These little pieces6 of DNA help switch on or boost the expression of specific genes, that control the development of the face and head before birth. What's interesting about these little influential bits of DNA is that a gene enhancer doesn't have to be found anywhere close to the genes and, in some cases, doesn't even have to be located on the same chromosome.
Of course, there are a number of hereditary(遗传) factors which help determine appearance, for example, a child resembles a parent. The researchers, who outlined their findings in the journal Science, said the gene enhancer adjusts the genes to give your face its final unique look. Even with identical twins, there are subtle
