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[audioFiles]2015m3s/audio_ezfj_ezflisteningd_20151_165[/audioFiles]

游客2024-09-27  14
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答案                 New Insight into the Roots of Homosexuality
    For an evolutionary biologist, homosexuality is something of a puzzle. It’s a common trait, found in up to 10% of the population. It appears to be run in families, suggesting that it is hereditary, at least in part. And yet it defies the very reason why traits are passed on from generation to generation. How could something that hinders childbearing be passed down so frequently from parents to children?
    Researchers at the National Institute for Mathematical and Biological Synthesis think they may have an answer. It’s not in written in our DNA sequence itself, they suggest, which explains why scientists have failed so far to find "gay genes", despite intensive investigations. Instead, it’s written in how our genes are expressed: that is, in certain modifications to how and when DNA is activated. These changes can have environmental roots, so are not normally permanent enough to be passed from parent to child. But occasionally, they are.
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