43 According to the research, which of the following is likely to have the lowest IQ?
(A) The first-born.
(B) The second-born.
(C) The second youngest.
(D) The last-born.

Does your older brother think he’s cleverer聰明 than you?

Well, he’s probably right. According to new research due to be published this week in the journal Intelligence情報, 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荷蘭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基本 effect on diverse多種多樣 factors, ranging from the risk of cancer, asthma氣喘 and eczema濕疹, to weight and even premature過早 death.

It can also affect personality, achievement, and career, with first-borns being more academically學術 successful and more likely to win Nobel prizes.

However, eldest children are less likely to be radical激進 and pioneering開創性.

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稀釋 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父母的 attention and stimulation刺激 will drop.

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.