Which has the greater effect on human behavior: nature or nurture? Hair color, height, and many other physical characteristics depend on genes, or nature, but the origin of behavior, intelligence, and personality is not so clear. Most scientists agree that both genes and the environment play a role in behavioral development, but disputes still rage over the degree of influence exerted by each.
先天遗传和后天环境，哪个对人类行为的影响更大？众所周知，一个人的头发颜色、身高和许多其他的生理特征可以由基因或先天因素决定，但决定人类行为方式、智力发展和个性特征的因素，至今却仍是未解之谜。大多数科学家都认可，基因和环境在人类的行为发展中扮演着重要角色，但这两者对人类行为产生的影响程度，至今仍未有定论。
A branch of psychology known as behavior genetics examines the genetic base of behavioral and personality differences among people. Behavior genetics is a controversial field, since misuse of psychological research into the genetic roots of behavior can have horrifying results. Several generations ago, psychologists and other scientists used arguments about the genetic influence on behavior and intelligence to support racist theories about the superiority of Anglo Americans. Moreover, these theories often became the foundation of public policies that discriminated against African Americans and Native Americans. Today, behavior geneticists carefully consider the potential political repercussions of their work.
作为心理学的一个分支，行为遗传学研究人与人之间行为和个性差异的遗传根源。行为遗传学是一门颇具争议的学科，如果错误地将心理学研究方法应用到遗传根源分析中，将对结果造成极大的误导。几个世纪以前，心理学家和有关科学家表示，基因会对人类行为和智力产生影响，他们利用这一论点来支撑英美人彰显优越性的种族主义理论。之后，歧视非裔美国人和印第安人的公共政策出台，这些种族主义理论意外成为了制定政策的理论基础。所以，当今社会，考虑到研究结果对政治产生的潜在影响，行为遗传学家必须对研究秉持高度的谨慎性。
Behavior Genetics is a branch of psychology that examines the genetic base of behavior and personality differences among people. An understanding of genetics begins with the following basic concepts:
A vast number of cells make up the human body. Each cell has forty-six chromosomes, which come in twenty-three pairs. The only exceptions are sex cells.
Sex cells are sperm in males and eggs in females. Each sex cell has only twenty-three chromosomes.
Chromosomes are made up of thin strands of deoxyribonucleic acid (DNA). Each chromosome pair contains thousands of genes.
Genes are segments of DNA that function as hereditary units. Genes are carried on chromosomes.
DNA is made up of units called Nucleotides. There are only four different nucleotides, labeled A, C, G, and T. Long strings of nucleotides make up genes.
Genes get translated into proteins, which carry out various functions in our bodies. For instance, some proteins serve as the building blocks of cells. Other proteins function as enzymes or hormones.
行为遗传学是心理学的一个分支，研究人与人之间行为和个性差异的遗传根源。深入理解基因学说，首先需要了解以下基本概念：
人体是由亿万个细胞构成的。每个细胞中有46条染色体，构成23对。人体的细胞中，唯一存在差别的是生殖细胞。
生殖细胞指的是男性的精子和女性的卵子。每个生殖细胞只有23条染色体。
染色体由呈双螺旋结构的脱氧核糖核酸(DNA)组成。每条染色体携带数千个基因。
基因是具有遗传效应的DNA片段。一条染色体携带多个基因。
DNA由核苷酸组成。四种核苷酸单体分别是 A、C、G、T。核苷酸单体配对形成的双链构成DNA分子。
基因组上的基因产生蛋白质，蛋白质实现了人体细胞不同的功能。例如，一些蛋白质成为细胞的组成部分。其他蛋白质构成酶、激素等生理活性物质。
Monogenic and Polygenic Traits单基因和多基因性状Some characteristics or traits are controlled by a single gene, which means they are Monogenic. A single gene, for example, can be part of what brings about alcoholism or schizophrenia. Most traits are controlled by the actions of several genes, which means they are Polygenic. For example, a person’s intelligence is linked to the combination of several genes. The environment also shapes traits, and later in this chapter we will discuss how genes interact with the environment to produce psychological traits.单基因性状指的是人类的某些特征或性状是由单个基因所控制的。例如，酗酒或精神分裂症产生的根源可能与某单一基因有关。多基因性状指的是人类的大多数性状是由几个基因共同决定的。例如，一个人的智力与多个基因组成的基因群有关。本文后面的章节会讲到，环境也会影响性状，而且，基因与环境的相互作用是造成人类某些心理性状的原因。
Heritability遗传可能性In a group of people, a particular psychological trait, such as intelligence, usually varies a lot. Differences in groups may be due to genes or the environment, and researchers use a statistic called heritability to see which has the largest influence. Heritability is a mathematical estimate that indicates how much of a trait’s variation can be attributed to genes. There are three important principles of heritability:
Heritability estimates don’t reveal anything about how much genes influence a person’s traits. These figures tell us only to what extent trait differences between people can be attributed to genes.
Heritability depends on the similarity of the environment for a group of people. In a group of people who share similar environments, heritability of a particular trait may be high. However, that same trait may have low heritability in a group of people who operate in different environments.
Even if a trait is highly heritable, it can still be influenced by environmental factors.
某种心理特征，比如智力，在一个群体中通常会体现出较大的差异。群体所展现的这种差异可能由基因或环境决定，为了确定最大影响因素，研究人员应用了一种叫做遗传可能性的统计方法。遗传可能性是一种数学估计方法，用于判断基因可以对一个性状的变异产生多大的作用。遗传可能性有以下三个重要原则：
遗传可能性的评估结果只用于说明基因对人的性状差异的影响程度，并不代表基因影响的具体量化数值。
一个群体所处的环境相似性会对遗传可能性产生决定作用。一个群体如果在相似的环境下，群体中的个体对某一特质的遗传力会很高。但是，如果群体处在不同的环境下，那么个体对某一特质的遗传力将会很低。
某种特质即使在很大程度上可以被遗传，也仍然会受到环境因素的影响。
Example: Imagine that ten people live in identical environments. Somehow, they experienced identical prenatal environments while in their mothers’ wombs, were raised in identical homes by parents who were identical in every way, and had all the same childhood and adulthood experiences. Suppose that these ten people turn out to be different with respect to one trait, such as the rate at which they can wiggle their ears. Since both genes and environment can influence traits, these differences would have to be genetic, since they could not be due to differences in environment. In such a case, heritability of the ear-wiggling trait would be close to 100 percent. Now suppose some of these ten people enter different ear-wiggle training camps. The camps vary in effectiveness, so the subjects in some camps increase their ear-wiggling rates, while other subjects remain the same. After the camp training, environment would account for some of the differences among the ten people in ear-wiggling ability. A smaller proportion of the differences would be due to genes alone. Therefore, heritability would be lower.
例如：假设有十个人生活在完全相同的环境中。条件如下，出生前，他们所经历的子宫环境相同，出生后，他们由相同的父母在同一家庭中抚养长大，童年和成长经历也完全相同。假设这十个人在某一特征上存在差异，比如他们摆动耳朵的速度不同。我们知道，基因和环境都能影响性状，那么在环境相同的条件下，这一性状的差异只能归结于基因原因。这种情况下，摇耳性状的遗传率将接近100%。现假设这十个人中，某一些人进入了耳部训练营。这些训练营的训练效果各不相同，经过训练后，有些个体的摇耳频率得到了提高，而其他个体的摇耳频率仍和之前一样。训练结束后，我们可以对比环境对摇耳能力这一性状产生的影响。由此总结，基因导致的性状差异越少，个体的遗传可能性就越低。
行为遗传学行为遗传学(behavioral genetics)是研究支配生物的向光、向地、摄食、求偶、育儿、攻击、逃避以及学习与记忆等行为的基因和基因表达的时间、场所及作用途径等的遗传学分支学科。行为是受基因控制的复杂的生物学过程。每一种生物都有它特殊的行为，越是低等的生物，行为模式就越单纯。但是各种生物的行为之间又有许多共同之处，所以对各种行为的遗传学研究既有阐明不同生物特殊行为的遗传基础的意义，又有普遍的生物学意义。
DNA双螺旋结构发明人、诺贝尔奖获得者Watson曾经说过：你可以继承DNA序列之外的一些东西，这正是现代遗传学让我们激动的地方。换言之，环境和成长经历也可能改变基因。表观遗传学正是要研究这个奥秘。
达尔文的自然选择理论在生命科学界得到了广泛的认同。按照达尔文的理论，长颈鹿的脖子之所以长，是因为短颈的无法吃到合适的食物而饿死了，只有长颈的得到了繁衍。现代遗传学的发展同样也证实了达尔文理论的正确性，按中心法则（genetic central dogma）的说法，遗传信息从DNA传递给RNA，再从RNA传递给蛋白质，即完成遗传信息的转录和翻译的过程。也可以从DNA传递给DNA，即完成DNA的复制过程。通俗来讲，DNA制造RNA，RNA制造蛋白质，蛋白质反过来协助前两项流程，并协助DNA自我复制，同时蛋白质也是真正形式体内功能的载体。简单来说，DNA是什么样，生物就会按照这个编码长成相应的个体。
但除此之外难道没有另外一种遗传的方式了吗？长颈鹿的脖子之所以长，会不会是因为其祖先代代都努力伸长脖子，从而将这个长脖子遗传了下去？
事实上，挑战中心法则的的现象也在不断涌现：一对同卵双胞胎，拥有近乎完全一致的遗传信息，但他们一方正常，一方患有红斑狼疮；老鼠的恐惧记忆可以遗传给下一代，甚至下下代；小鼠在闻到以前给予它们父亲(或是祖父)留下电击恐惧感的气味之时，会表现出恐惧；某些特定的行为和生活经历能够被遗传等等。这些现象似乎暗示，除了DNA序列之外，还有其他方式影响着遗传。为此，致力于这类现象的研究产生了一个新的学科——表观遗传学。
表观遗传学，被人们认为是“新遗传学”。简单来讲，就是研究DNA序列不变，但基因表达可遗传的一门遗传学分支学科。自1942奥地利发育生物学家Conrad Waddington首次提出表观遗传学（Epigenetic）概念，表观遗传学得到了广泛的关注和蓬勃的发展，已经成为生命科学领域的前沿和热点，而应用最为广泛的就是针对表观遗传调控因子进行靶向药物设计，进行新药研发。你怎么看？欢迎大家文末给阿伦老师留言！
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