a blank slate 如一张白纸

    The idea that the human personality is a blank slate, to be written upon only by experience, prevailed for most of the second half of the 20th century. 人的性格有如一张白纸，唯有经历才能在上面挥毫泼墨——这个观点几乎在整个二十世纪下半叶都十分流行。

    be undermined 逐渐减弱

    Over the past two decades, however, that notion has been undermined.  然而近二十年来，此观点的说服力已逐渐减弱。

    govern whether people are happy or unhappy 决定一个人幸福与否

    As any human being knows, many factors govern whether people are happy or unhappy. 众所周知，决定一个人幸福与否的因素有很多。

    external circumstances  外部环境

    better-off people 富裕的人

    External circumstances are important: employed people are happier than unemployed ones and better-off people than poor ones.  外部环境就十分重要：就业人群比失业人士更幸福，富裕阶层比家境贫寒的人更幸福。

    has a role too 也是一个因素

    the middle-aged 中年人

    Age has a role, too: the young and the old are happier than the middle-aged. 年龄也是一个因素：年轻人与老年人比中年人更幸福。

    determinant 决定性因素

    But personality is the single biggest determinant: extroverts are happier than introverts, and confident people happier than anxious ones.

    但是，性格是唯一一个最大的决定性因素：性格外向的人比性格内向的人更幸福，自信的人比性格焦虑的人更幸福。

    is at least partly heritable 在某种程度上是遗传的

    the tendency to be happy or miserable 一个人感到幸福还是悲伤的倾向

    is passed on through DNA 由基因传递

    That personality, along with intelligence, is at least partly heritable is becoming increasingly clear;  so, presumably, the tendency to be happy or miserable is, to some extent, passed on through DNA.  性格与智力至少在某种程度上是遗传的，这个观点正变得越来越明确；所以，在某种程度上，一个人感到幸福还是悲伤的倾向可能是由基因传递的