  How might one harm a child through choosing genetic traits? Perhaps by selecting for traits that clearly cause significant suffering and a typically short life span (e.g., Tay-Sachs disease, Lesch-Nyhan syndrome). Such constraints may seem unnecessary, given that most parents do not intentionally desire painful states for their children and would not seek to engineer them in this way. Also, relatively few genetic conditions will be so inherently debilitating as to make life so obviously miserable that would prevent one to consider that life is, on balance, a benefit.