englishmelon
Listen to the audio and fill in the blanks with the exact words / phrases missing. You can play and pause the audios for a maximum number of 10 times.
You hear a talk by Professor Jaquiline Jaccard on the role played by twin studies in understanding behavioral genetics. Now, listen to the audio as many times as you need to understand all the words. You should view the answers only after having tried your best.
Audio
Twin studies remain a favorite tool of behavioral geneticists. Researchers have used twin studies to try to disentangle the environmental and genetic backgrounds of varieties of traits, from (1) ________________________________ to intelligence; to (2) ________________________________ to alcohol dependence. However, despite the (3) ________________________________ of twin studies, some psychologists have long questioned assumptions that underlie them, like, the supposition that (4) ____________________ and (5) ______________________ twins share equal (6) ___________________________ or that people choose mates with traits unlike their own. The equal environments assumption, for example, has been debated for at least (7) __________________. Many researchers have found (8) ________________________ that the assumption is valid, but others remain skeptical.
Overall, twin studies assumptions remain (9) ___________________________. In response, though, researchers are working to expand and develop twin study designs and statistical methods. And while the assumptions remain a (10) ___________________________ ________ for some researchers, many agree twin studies will continue to be an (11) ___________________________, along with emerging genome and (12) ___________________________ ________________________ – in shedding light on human behavioral genetics.
The classical twin study design (13) _______________________ studying twins raised in the (14) _______________________ environments. Monozygotic, or (15) _______________________, share all of their (16) _________________, while dizygotic or (17) _______________________ share only about 50 percent of them. So, if a (18) __________________ compares the similarity between (19) _______________________ ________________ to the similarity between sets of fraternal twins for a (20) _______________________ _____________, then any excess (21) ___________________ between the identical twins should be due to genes rather than environment.
Researchers use this method, and (22) _______________________ on it, to estimate the (23) ____________________ of traits – the percentage of variance in a population due to genes. Modern twin studies also try to (24) __________________ the effect of a person’s shared environment, family the best example, and (25) _______________________, which is the individual events that shape life.
It is assumed that people are as likely to choose (26) ______________ who are different from themselves as they are to choose partners who are (27) _________________ for a particular trait. If, instead, people tend to choose (28) _______________ like themselves, then fraternal twins could share (29) _______________________ _____________________ of their genes – and hence, more similarities on (30) _______________________ ________________________ – because they would receive similar genes from their (31) _______________________ ___________________________.
It is also assumed that fraternal and identical twins raised in the (32) _______________________ ___________ experience equally similar environments; but some research suggests that parents, teachers, (33) ________________ and others may treat identical twins more similar than fraternal twins.
Some researchers think that (34) _______________________ between genes and environment, rather than genes and environment separately, may influence many traits. A recent study suggests that a gene might moderate (35) _______________________ _______________, particularly in people who are severely (36) _______________________ as children. Many twin study designs don’t take (37) _______________________ ___________________ into account.
Traits can be inherited through different (38) _______________________ _______________. For traits governed by dominant genetic mechanisms, a dominant gene inherited from one parent triumphs a recessive gene inherited from the other parent: If a person inherits a (39) _______________________ gene for blue eyes from one parent and a dominant gene for (40) _______________________ from the other parent, then the dominant brown gene wins, and the person’s eyes are brown.
Next: Answers
Do to procced to the answers without having tried to understand all the missing words and phrases.
