【英语时差8,16】为什么禁止近亲结婚？

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It’s a distressing¹ fact that human activities are causing the wide-scale extinction² of other species on earth. Something you may not know, however, is that the fewer animals there are in a given species, the more at risk that species is — and not just because it’s easier for a small group to disappear than a large group. Another danger is inbreeding. Inbreeding is the term used when animals mate with their relatives. All animals, including humans, inherit half their genes³ from their mothers and half from their fathers. Within certain limits, it’s good for offspring to have a father whose genetic⁴ makeup⁵ is significantly different from its mother’s. It’s kind of like poker⁶. Reshuffling the deck makes it more likely you’ll draw a good hand by chance. If the deck were only sixteen cards, each of which appeared twice, the chances of getting a good hand would be much lower.

 

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