Designer Babies

There are many different opinions people have when it comes to these "designer babies". I believe that if you could save another child's life by having another child which is "designed" so that it could help the child then it should be allowed. Yes it is un-natural, but it's saving lives. If i was a child created to help my sibling I honestly wouldn't care. I believe I would feel good about myself, saving someone I love. Some people say that it isn't right but what if the parents really wanted another kid? Who's to know the truth.