To conclude, it is unfair to believe that the human nature completely explains one’s future crimes, as external factors are more decisive.

To conclude, it is unfair to believe that human nature or the genes completely account for why some people commit crimes, since external factors may be more decisive.

* 补充了or the genes。the genes这个词汇的使用很有意思。

* explains 换成了 account for，只是一种替换，就是补充词汇吧。

* one’s future crimes 换成了why people commit crimes。因为future crimes给人感觉这个人将来就是注定要犯罪的，而why some people commit crimes不是这个意思，就不会给人这个感觉，尤其是有some 这个词缩小了人群的范围。

* 引导原因状语从句的as换成了since，更合理。as的“因为”意义偏向“于此同时”，since的“因为”意义偏向“既然”。那么，因为前文已经仔细讨论过了external factors may be more decisive，所以，在结尾处用since更合理。