人为的失误可能是一个起作用的因素。

Human error may have been a contributing factor.

《牛津词典》

然而，近日的双胞胎研究帮助科学家们得出了一个全新的结论：先天和后天因素不是唯一起作用的因素。

Lately, however, twin studies have helped lead scientists to a radical new conclusion: that nature and nurture are not the only elemental forces at work.

youdao

另一个起作用的因素是人口总规模。

Another factor at work here is sheer size.

youdao