题目内容：
Questions are based on the following passage．Recently, a controversial study on twins claims to provide evidence that the genes we inherit have a bigger impact on exam success than schooling and parenting．
The study was designed by Robert Plomin at King's College London and his colleagues, to make clear the impact of genes and the environment on educational achievement． The key objective was to see how exam scores varied from the national average depending on whether twins had the same genetic make-up, as identical twins do, or shared only half of their genes, which is true for non-identical twins． Each pair shared the same environment and schooling．
It seems that nature defeats nurture． The team looked at 5474 pairs of twins--2008 of them identical--and analyzed their achievement in GCSEs (普通中等教育证书) ． They found that genetics accounted for 52 percent of the differences between exam scores． A shared upbringing accounted for 36 per cent of the differences, with the remainder influenced by other factors that weren't shared, such as having a different teacher．
What does this mean for children who haven't inherited academic genes? "Marginalization (边缘化) of the 'less gifted' does not follow from finding genetic influence on educational achievement," says Plomin．"If anything the opposite is true--we need to provide more resources for those who need the most help．"
Plomin also says that, although it is too early for these results to have an impact on our education system, the findings should inform debate on how education is delivered． "One strong implication of recognizing genetically driven differences between children is to personalize education as much as possible, rather than imposing a one-size-fits-all (一刀切) approach," he says．
Some researchers are suspicious, including Steven Rose of the UK's Open University． He says that twin studies are "subject to difficulties of interpretation"． For instance, the unusual upbringings of identical twins---often wearing exactly the same clothes or being confused with one another---constitute an environmental impact that could be overlooked． But he agrees with Plomin that child-focused rather than rote (死记硬背) education is the way forward． "In an ideal school environment, individual aptitudes should be encouraged, but you don't need to, and nor would it be feasible to sequence a child's genome (基因组)to discover what these aptitudes might be," he says．
Even if it were possible to analyze every child's genetics, no single genes for intelligence have yet been identified, says Sarah Norcross of the UK Progress Educational Trust． Most studies so far have found that educational achievement is influenced by a combination of thousands of genes． "We don't even understand the genetics of height yet, which is very easy to measure," says Norcross． "So we are light years from applying this type of thing to education．"
According to the study, which of the following pairs is most likely to have similar academic achievements? A．Identical twins with a shared upbringing．
B．Non-identical twins with a shared upbringing．
C．Identical twins with different teachers．
D．Non-identical twins with the same teachers．
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