Since above-average height correlates with above-average income, and there is a clearly a genetic component to height, it is not fanciful to imagine couples choosing to have taller children. The outcome could be a genetic “arms race” that leads to taller and taller children, with significant environmental costs in the additional consumption required to fuel larger human beings.
就性别挑选而论，不难看出，不同的夫妇分别为自己的子女做出最佳的选择，结果却可能使所有孩子的处境还不如无法挑选子女性别的时候。其他形式的基因筛选也可能出现相似的情景。由于较高的身材与较高的收入有联系，而身高显然又有基因方面的原因，那么可以想象，人们大多会选择生育身材较高的子女，结果可能引发一场基因上的“军备竞赛”，致使孩子们的身材越来越高，对环境造成极大的消耗，因为人类体型增大，消耗越大。