单选题 Researchers have known for years that children whose mothers were chronically stressed during pregnancy—by famine, anxiety, the death of a relative or marital discord, for instance—show higher-than-normal rates of various psychological and behavioural disorders when they are adults. They have also known for a long time that those brought up in abusive environments often turn out to be abusive themselves. The second of these observations is usually put down to learning. The reason for the first has remained unclear. A study just published by Axel Meyer, Thomas Elbert and their colleagues at the University of Konstanz in Germany, however, points to a phenomenon called epigenetics as the likely answer. Epigenetics is a type of gene regulation that can be passed from a cell to its daughters. The most common mechanism is methylation, whose consequence is to inactivate the gene being methylated.
They found that women abused during pregnancy were significantly more likely than others to have a child with methylated glucocorticoid-receptor genes. By contrast, abuse before or after pregnancy resulted in no such correlation. Nor was the mother"s own methylation affected by violence towards her. Taken together, these results suggest that glucocorticoid-receptor-gene methylation happens in the fetus in response to a mother"s stress, and persists into adolescence.
This has implications for those adolescents" long-term health. Dampened glucocorticoid-receptor-gene activity has been shown to increase the risk of obesity and of depression. It also makes people more impulsive and aggressive—and therefore, if male, more likely to abuse the pregnant mothers of their children, thus perpetuating the whole sorry cycle.
Why, in light of such negative effects, have humans evolved to be programmed this way while still in the womb? Part of the answer is probably that not all the negative consequences would have shown up at the time the mechanism was evolving. The other part is that some of the consequences probably have a positive effect.
What can be done with such knowledge is unclear. Drugs that demethylate DNA are under development, but are still some way from approval—and, in any case, interfering with epigenetics, which is a widespread mechanism of gene regulation, is a drastic approach. The research might, though, point to the period when intervening to stop abuse will have the greatest effect. Then again, such intervention is always desirable, for the sake of both mother and child.

单选题 According to Paragraph 1, which of the following is NOT true?

【正确答案】 C

【答案解析】[解析] 细节题。根据题干关键词定位到第一段。根据首句“如果母亲在怀孕期间长期遭受……过大压力，她们的孩子成年后出现各种心理疾病和行为问题的概率会高于平均概率”和第五句“一种被称为‘外因遗传’的现象很有可能就是这个问题的答案”，可知C项说法不严谨，以偏概全，违背了原意，并非只要孩子一出现心理问题和行为障碍就是外因遗传引起的，故C项为正确答案。A、B、D三项是对原文第一、二、三句的变相描述，说法均符合文意，故排除。

单选题 A child with methylated glucocorticoid-receptor genes has a mother ______.

【正确答案】 A

【答案解析】[解析] 细节题。根据题干关键词定位到第二段。该段末句提到“总体看来，这些结论表明胎儿糖皮质激素受体基因的甲基化是由于母亲压力过大引起的”，故A项为正确答案。根据第二句中的no such correlation，可排除B、D两项。C项的干扰性较大，该段第一句说的是“孕期中遭到虐待的母亲生下糖皮质激素受体基因被甲基化的幼儿的可能性要比其他母亲高得多”，C项错把“可能性”当成“必然性”，故排除。

单选题 The word "Dampened" (Para. 3) most probably refers to ______.

【正确答案】 D

【答案解析】[解析] 含义题。根据题干关键词定位到第三段。根据前三个自然段，可知Dampened glucocorticoid-receptor-gene activity仍然指“methylated glucocorticoid-receptor genes”，而methylated的定义在第一段末句给出了，句中的inactivate与D项表达的意思一致，故D项为正确答案。long-lasting"持久的”和attached“附着的”，均不是该单词的正确释义。虽然Dampened有“潮湿的”之意，但此处并未取这层释义，故排除B项moist(潮湿的)。

单选题 It can be implied from the last two paragraphs that ______.

【正确答案】 D

【答案解析】[解析] 推断题。根据题干关键词定位到第四、五段。第五段末句提到“为了让母亲和孩子们都幸福，这样的干涉乃众望所归”，故D项推断正确。第四段第二句指出“也许部分原因是，当甲基化作用还在进化的时候，所有的消极影响不会当即全部表现出来”，所以，“肥胖症其实在极少情况下是天生的”，故A项推断错误。根据外因遗传现象和B项内容可知，她的后代应该是对害怕情绪“敏感”，B项错在insensitivity一词。C项偷换概念，把原文中主语Drugs偷换为The research，故排除。