Humans
人类
In humans, probably the most common genetic disorder caused by inbreeding is spinal muscular atrophy (SMA). SMA causes the death of the cells in the spinal cord, and is often fatal or severely disabling.
在人类中，由近亲繁殖带来的最普遍的遗传缺陷可能是脊髓性肌肉萎缩症。这种疾病会导致脊髓中的细胞死亡，最后可能会致命或造成严重残疾。
SMA is caused by an abnormal version of a gene on chromosome 5. About 1 in 50 people have this abnormality, which means 1 in 100 people will contribute it to their children . . . and, therefore, 1 in 10,000 people (100 times 100) will inherit the defective gene from both parents.
脊髓性肌肉萎缩症是由5号染色体上的一个基因异常造成的。平均每50人中就会有一个人的这个基因出现异常，这意味着每100个人就会有一个人把它遗传给他们的孩子……因而每1万人（100×100）中，就会有一个人从父母那里都继承到这种有缺陷的基因。
If a parent has a child with his- or herself, on the other hand, the chance of SMA is 1 in 400-since if he or she has a copy of the defective gene (1 in 100), there 8217;s a 1 in 4 chance it will be the child 8217;s only copy.
如果一个人打算自体繁殖，那么得病的几率为四百分之一——他自己有这种缺陷基因的几率是百分之一，而又有四分之一的几率他的孩子只会继承到这个基因。
One in 400 may not sound so bad, but SMA is only the start.
四百分之一的几率听起来还不算太糟糕，但这仅仅是个开始。
DNA is complicated
复杂的DNA
DNA is source code for the most complex machine in the known universe. Each chromosome contains a staggering amount of information, and the interaction between DNA and the cell machinery around it is incredibly complicated, with countless moving parts and Mousetrap-style feedback loops. Even calling DNA “source code” sells it short-compared to DNA, our most complex programming projects are like pocket calculators.
DNA是宇宙中已知的最复杂机械的源代码。每一条染色体上都包含巨量的信息。而DNA和周围细胞工厂的相互作用又极其复杂，包含了无数的移动部件和捕鼠器式的反馈循环。甚至把DNA称作源代码都太小看它了。与DNA相比，我们最复杂的编程项目看起来就像便携式计算器那样简单。
In humans, each chromosome affects many things through a variety of mutations and variations. Some of these mutations, like the one responsible for SMA, seem to be entirely negative; the mutation responsible has no benefit. In our D D system, it 8217;s like a chromosome having an STR of 1. If your other chromosome is normal, you 8217;ll have a normal character stat; you 8217;ll be a silent “carrier.”
在人体中，每条染色体通过一系列的突变和变异影响着许多其他的东西。其中一些突变，就像造成脊髓性肌肉萎缩症的那个突变，产生的结果完全是负面的，这种基因突变是没有益处的。在《龙与地下城》系统中，它就像力量值为1的染色体，如果你的其他染色体都是正常的，那么你的整体属性值也将会是正常的，但你是一个隐形的“携带者”。
Other mutations, like the sickle-cell gene on chromosome 11, can provide a mix of benefit and harm. People who have the sickle-cell gene on both their copies of the chromosome suffer from sickle-cell anemia. However, if they have the gene on just one of their chromosomes, they get a surprise benefit: extra resistance to malaria.
其他的突变，比如11号染色体上镰状红细胞基因，既会带来好处也会带来坏处。如果一个人的两条遗传序列上都有镰状红细胞基因，那么他们就会得镰状红细胞贫血症；如果他们只有一条遗传序列上有这种基因，就会产生一个意料之外的好处：对疟疾的额外免疫性。