遗传学的发展——尤其是人类基因组图谱的绘制——非常令人兴奋。例如，如果我们能正确识别疾病携带的基因，我们可能能够根除癌症。但新的知识赋予我们新的能力。新的能力给我们带来了新的道德困境。这在生物学领域是如此真实，以至于出现了一个全新的学科——生物伦理学。

当人们想到遗传学和生物伦理学时，“设计婴儿”是一个常见的幽灵。如果你只是想象一下父母选择拥有没有缺陷的基因天赋的孩子，这听起来是相当良性的。但一想到权力和知识掌握在当代希特勒手中，就令人胆战心惊。

But at this point, the idea of designer babies is amyth, not a scientific reality. We can’t literally reach into an embryo and just give it the genes we want. We don’t have that kind of power.

But perhaps we can get the same effect by the backdoor. We can use our vast new knowledge of the human genome to decide whether or not to implant embryos on the basis of their genetic make-up – without having to design the genes directly. This is what’s called “PGD” - pre-implantation genetic diagnosis. Suppose a couple is worried about passing on a genetic disease. Their eggs and sperm are combined to produce embryos outside of the womb. These are tested, and only the disease-free ones get implanted. This seems like the parents’ right, and a good thing.

Suppose, however, that deaf parents choose an embryo that will produce a child that will share their deafness? Arguably, deafness is not an intrinsic defect, but a social handicap in a world where there are lot of hearing people, and the structures for attaining and dispersing information are designed for the hearing. Such a decision strikes me as morally problematic. Why should parents deny a child a trait that, valuable and interesting as Deaf culture may be, is certainly a valuable trait to have? One could argue, however, that the particular child involved would not have existed had the parents chosen a different embryo. Does the child have a complaint; if the choice to have a hearing child would have meant that he or she wouldn’t have existed? Here metaphysics, genetics, and ethics conspire to make things difficult.

Where it’s legal to do so, you can use PGD to make sure you have a boy rather than a girl. Perhaps parentsshouldhave the freedom to choose the gender of their offspring. But an unfortunate pattern of individual decisions could lead to a gross imbalance in the sexes --- like the shortage of marriageable females in China, as a result of the “one-child” policy, and the disproportionate aborting of female fetuses.

那么，父母使用PGD来确定头发或眼睛的颜色，或确保他们的孩子肤色较浅或较深呢?一个人可能不喜欢控制自己孩子外貌的欲望。但这会是不道德的吗，还是在父母的权利范围内?很难确定改变蓝色眼睛和棕色眼睛在人口中所占比例的长期后果，但谁知道呢?

How about choosing traits like intelligence and athletic ability? Or what about cases where, in the interest of family unity and empathy, clumsy parents choose to have a child with limited athletic ability, or happily normal parents make sure that their child won’t be extremely intelligent.

Perhaps mercifully, here we have gotten back into the realm of sciencefiction, not sciencefact. According to my no doubt superficial understanding of things, such choices would require knowing more about how genes produce traits than we actually do. With some diseases – and perhaps some basic traits, like hair color – we may have a good idea of which genes make the difference. But athletic ability and intelligence depend on a whole host of factors, not just one gene. So nothing like what we are imagining is on the horizon.

尽管如此，我们的知识和力量正在超过我们的智慧，这是一个明显的危险。回到性别的例子上，似乎人类的繁殖已经进化到只产生略多于女性的雄性。一旦我们开始胡搞繁殖，自然的性别平衡就会完全失衡。这可能会对我们的文化和社会产生巨大的负面影响。

Another issue is how much of what can be determined about a given person’s genetic traits should be known, and by whom it should be known. For example, we can now determine whether a person has certain genes that predispose her or him to Alzheimer’s. I’d kind of like to know this about myself; at 70, I might eschew long term projects if I am predisposed, and be more willing to start a multi-volume work if I am not. My doctor is skeptical; she points out that if I have the gene, there is nothing I can do about it. She means that there is no cure; the knowledge would just make me miserable. I think she is a little unimaginative. Do I have the right to know everything that can be known about me, if I can handle the expenses? Does it ever make sense for physicians to know something about me, and refuse to share it with me?

所以，有很多可以讨论的，我们请来了一位非常棒的嘉宾来讨论这些问题，他是斯坦福哲学博士David Magnus，他现在是斯坦福医学院的常驻伦理专家。

Photo byNational Cancer InstituteonUnsplash