时差N小时 近亲生育的危害(下)

Prolonged interbreeding in any species can eventually lead to serious birth defects.

长期来看，任何物种间的异血缘繁殖终会导致严重的先天缺陷。

Harmful genetic¹ mutations are less likely to appear in large populations where individuals reproduce with random² partners due to the wider variety of genetic mutations.

人口多的地方，个体间随机繁衍，恶性基因突变的几率降低很多，因为基因突变的种类更广泛。

But in small, isolated³ populations where inbreeding is common, there’s a greater chance that related partners carry the same mutations.

反之，在人口小且封闭的地方，近亲交配的现象十分普遍，有血缘的伴侣携带相同基因突变的几率更大。

However, harmful effects are more common in groups with a history of interbreeding over several generations.

然而，恶性先天缺陷常见于家族多代异血缘交配。

First cousins that are not from such groups run only a slightly greater risk of producing children with birth defects than non-related couples.

表亲生育的孩子患先天缺陷的风险略高于无血缘伴侣生育的孩子。

Although such risks should not be ignored, first cousin marriage is not necessarily a recipe for genetic disaster.

虽然这样的风险不容忽视，但是表亲结婚并非注定会引发基因灾难。

1 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

2 random   

adj.随机的；任意的；n.偶然的(或随便的)行动

参考例句：

• The list is arranged in a random order.名单排列不分先后。
• On random inspection the meat was found to be bad.经抽查，发现肉变质了。

3 isolated   

adj.与世隔绝的

参考例句：

• His bad behaviour was just an isolated incident. 他的不良行为只是个别事件。
• Patients with the disease should be isolated. 这种病的患者应予以隔离。