The genetic predisposition of a child is determined by his influence from both the father and the mother. His tendency to be healthy or sickly could be predicted by the genetics of both families. If, unfortunately, the child is to become sickly in the future, it would be better to know early so that appropriate actions could be taken and complications could be prevented. But as parent, what would you do if your child is born sickly and you discovered late? What if his condition is aggressively advancing?
Consider this scenario: your sick child will need to undergo various laboratory procedures and operations to maintain being functional. He would need blood, stem cells, and perhaps some organ. It is known that the most compatible donor (for anything) is a sibling since both of them came from combination of your genetic make-up and of your spouse’s. You wouldn’t let your sick child die, right? The question now is: would you be willing to have your other child to be a donor for whatever your sick child might need? Instantly you would answer yes since that child will be able to help his sibling, and the goal here is to keep the sick child alive. But is it morally right to do that to healthy child?
Parents reason out that not doing that would put the sick child in danger and it is morally wrong as a parent to let that happen. But have you considered what you take away from your healthy child by doing that? You take away his right over his own body. Yes, he would want to help his sibling because he loves him. But when his existence revolve only on making his brother live and people expect him to put others first before himself, there would come a time when he would question his very existence. Did he only exist to ensure that his brother lives? To some point, yes. However, he is also a person who has rights and he shouldn’t be denied of these.