PrepTest 137, Section 3, Question 13
Psychologist: Identical twins are virtually the same genetically.(51 more words not shown)
Which one of the following,(8 more words not shown)
- AMany people, including(14 more words not shown)
- BWhile some studies(20 more words not shown)
- CScientists are far(11 more words not shown)
- DIdentical twins who(19 more words not shown)
- ETwins who are(10 more words not shown)
Reading the argument
The twins were separated at birth and raised in vastly different environments. We have to accept that. Saying ‘Of course they're similar; they had the same parents and childhood’ would ignore the evidence we're supposed to evaluate.
Their similarities do give genetics a plausible role. But the psychologist goes further: many inclinations must be genetic and are not subject to environmental influence. Evidence of a genetic contribution doesn't automatically establish that environment cannot affect those inclinations.
What we’re looking for
I don't have a complete alternative explanation to predict here. That's okay. For this weakener, I'll keep the strong conclusion in view and ask whether an answer shows a relevant way environment still matters. We shouldn't reject the evidence merely because we don't yet see the answer.
Working the answers
- A
People can change their lifestyles, but what causes the change? The answer doesn't tell us. Changes might have genetic influences too, or might concern features outside the inclinations at issue. Change alone doesn't establish the environmental influence needed to challenge the psychologist's explanation.
- B
A few differences can coexist with many genetically influenced similarities. The psychologist hasn't claimed that identical twins match in every characteristic. Finding some differences doesn't directly show that the similar ethical beliefs, dress, or career inclinations are subject to environmental influence.
- C
Not yet identifying the specific genes doesn't mean genes have no effect. We could have evidence that genetics matters while lacking a detailed account of which genes do what. A limit on present scientific understanding isn't, by itself, evidence against a genetic explanation.
- DCorrect
These twins have virtually the same genes, yet growing up together gives them a reason to choose different paths: they want to distinguish themselves from each other. Their relationship with a sibling affects their beliefs, tastes, and careers. That is environmental influence on the very kinds of inclinations we're discussing.
Don't dismiss D just because these twins grew up together while the original study's twins grew up apart. The conclusion reaches beyond that study to how our inclinations arise. This new case shows that having the same genetics doesn't insulate those inclinations from an environmental influence. Genetics can still matter; it doesn't have to settle the outcome by itself.
- E
Nonidentical twins differ genetically. Their different beliefs, tastes, and careers therefore don't challenge the explanation that genetic differences influence such outcomes. D is more revealing because it keeps the genetics virtually the same and identifies an environmental reason for different choices.
More Weaken questions
Learn the LSAT our way
Our platform drills Weaken questions at your level and adjusts as you improve.