not only may agencies select for genetic traits,some fear parents may start to as well in what might be considered the most extreme application of genetic information-designing children.

参考答案:

要点:该句主干结构是not only...but also,因为用了as well,but aslo省略了。这句话倒装是因为not only放在句首。翻译时应正装。

译文：人们担心不仅各类机构会因为基因特征的不同而对人挑肥拣瘦，就连作父母的都有可能利用基因来设计婴儿——这可以说时把基因知识应用到了极端！