What Does Kurston Mean by Improving Fitness?

The dangers center around two key questions. What does kurston mean by improving fitness? And what does he mean by guiding reproduction? Hes can either mean something acceptable or something nightmarishy, horrible. An acceptable version of improving fitness would be eliminating genetic diseases through acceptable means. For example, letting married couples know whether their children will have a significant risk of having a serious genetic defect,. and then use moral means like natural family planning.