Course Hero Logo

Cambridge IELTS 11 Academic Reading Test 4.docx - Cambridge...

Course Hero uses AI to attempt to automatically extract content from documents to surface to you and others so you can study better, e.g., in search results, to enrich docs, and more. This preview shows page 1 - 2 out of 7 pages.

Cambridge IELTS 11 Academic Reading Test 4READING PASSAGE 1You should spend about 20 minutes onQuestions1-13which are based on Reading Passage 1 below.Research using twinsTo biomedical researchers all over the world, twins offer a precious opportunity to untangle the influence of genesand the environment – of nature and nurture. Because identical twins come from a single fertilized egg that splitsinto two, they share virtually the same genetic code. Any differences between them -one twin having youngerlooking skin, for example – must be due to environmental factors such as less time spent in the sun.Alternatively, by comparing the experiences of identical twins with those of fraternal twins, who come fromseparate eggs and share on average half their DNA, researchers can quantify the extent to which our genes affectour lives. If identical twins are more similar to each other with respect to an ailment than fraternal twins are, thenvulnerability to the disease must be rooted at least in part in heredity.These two lines of research – studying the differences between identical twins to pinpoint the influence ofenvironment, and comparing identical twins with fraternal ones to measure the role of inheritance – have beencrucial to understanding the interplay of nature and nurture in determining our personalities, behavior, andvulnerability to disease.The idea of using twins to measure the influence of heredity dates back to 1875, when the English scientist FrancisGalton first suggested the approach (and coined the phrase ‘nature and nurture’). But twin studies took a surprisingtwist in the 1980s, with the arrival of studies into identical twins who had been separated at birth and reunited asadults. Over two decades 137 sets of twins eventually visited Thomas Bouchard’s lab in what became known as theMinnesota Study of Twins Reared Apart. Numerous tests were carried out on the twins, and they were each askedmore than 15,000 questions.Bouchard and his colleagues used this mountain of data to identify how far twins were affected by their geneticmakeup. The key to their approach was a statistical concept called heritability. in broad terms, the heritability of atrait measures the extent to which differences among members of a population can be explained by differences intheir genetics. And wherever Bouchard and other scientists looked, it seemed, they found the invisible hand ofgenetic influence helping to shape our lives.Lately, however, twin studies have helped lead scientists to a radical new conclusion: that nature and nurture arenot the only elemental forces at work. According to a recent field called epigenetics, there is a third factor also inplay, one that in some cases serves as a bridge between the environment and our genes, and in others operates onits own to shape who we are.

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 7 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Fall
Professor
peter wan
Tags
Test, Twin, Thomas Bouchard

Newly uploaded documents

Show More

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture