以下是2014年12月英语四级听力短文第一篇文字版：

Passage 1

Scientists know how twins were born, now though, they are trying to explain how being half of the biological pair influences a twin’s identity. They want to know why many identical twins make similar choices even when they don’t leave near each other. For example, Jim Springer and Jim Louis are identical twins. They were separatedwhen they were only 4 months old. The two Jims grew up in different families and did not meet for 39 years. When they finally met, they discovered some surprising similarities between them. Both men were married twice, their first wives were named Linda, and their second wives were both named Betty. Both twins named their first sons James Allen. Scientists want to know what influences are personality. They study pairs of identical twins who grew up in different surroundings, like Jim Springer and Jim Louis. These twins help scientists understand the connection between environment and biology. Researchers at the University of Minnesota, studies 350 sets of identical twins who did not grow up together. They discovered many similarities in their personalities. Scientists believed that personality characteristics such as friendliness, shyness and fears are not result of environment. These characteristics are probably inherited. Scientists continue to study identical twins because they are uncertain about them and have many questions. For example, they want to know ‘can twins really communicate without speaking’, ‘can one twin really feel another twin’s pain’. Perhaps with more research, scientists will find the answers。

16. What are scientists trying to explain according to the passage?

17. What do we learn about the twin Jims?

18. Why are scientists interested in studying identical twins raised in different families?