哪位大牛帮忙解释一下这个题目和选项什么意思.

19. Identical twins tend to have similar personalities; if environment outweighs heredity in personality development, twins raised together should presumably have more similar personalities than those raised apart. A recent study of identical twins in both situations measured 11 key traits through a questionnaire, and concluded that 7 of the 11 are primarily products of heredity.

Which of the following, if established, would cast the most doubt on the study’s results?

(A) Fewer than half of the pairs of twins studied were raised separately.

(B) The ages of all of the twins studied fell within a 10-year range.

(C) Some of the traits that the study attributed to heredity developed in the separately raised twins because those pairs all grew up in similar families.

(D) Although over half the traits measured were determined to be linked to heredity, the nature of those traits varied widely.（C）

(E) The 11 traits that were measured constitute a representative sample of larger, generally accepted pool of key personality traits.

题目说,如果环境因素比遗传因素更能使双胞胎具有更多的性格相似点,那么同一环境一起成长的双胞胎要比在不同环境成长的双胞胎具有更多相似性.但一份研究通过问卷调查11个相似特征,表明在这两种情况下,有7个是由于遗传.

就是说,研究认为是遗传比环境使双胞胎具有更多相似.

这是个削弱题.削弱研究的结论.

C指出了,在不同环境长大的双胞胎实际上是在同一环境,---不同的家庭不代表环境不同.而研究的假设是不同家庭即是不 同的环境.