請依下文回答第 41 題至第 45 題
Does your older brother think he’s cleverer than you? Well, he’s probably right. According to new research due to be
published this week in the journal Intelligence, the oldest children in families are likely to have the highest IQs, and the
youngest the lowest.
The research is based on more than 1,000 children whose IQ was tested through childhood and adolescence up to the
age of 18. The Dutch study shows a birth-order effect on intelligence in each of the tests. Overall, the IQ of the first-born
child was higher than the second-born, which, in turn, was greater than that of children who had two or more older
siblings.
This is only the latest research to suggest that the order of birth can have a fundamental effect on diverse factors,
ranging from the risk of cancer, asthma and eczema, to weight and even premature death. It can also affect personality,
achievement, and career, with first-borns being more academically successful and more likely to win Nobel prizes.
However, eldest children are less likely to be radical and pioneering. Charles Darwin, for example, was the fifth child of
six.
Exactly why there should be such differences is not clear, and there are a number of theories, with many homing in
on environmental influences on the child. The so-called dilution theory, for example, suggests that as family resources,
both emotional and physical, as well as economic, are finite, it follows that as more children come along, the levels of
parental attention and stimulation will drop.
【題組】45 What does the phrase “homing in on” in the last paragraph mean?
(A) Overlooking. (B) Doubting. (C) Paying attention to. (D) Being responsible for.