If a child is born with certain weakness or disability whose fault it is?

I personally think that it's no one's fault really. It doesn't mean that a couple who is healthy and able-bodied will produce healthy and able-bodied children. And it doesn't always mean that less than healthy parents will produce sick or weaker babies. Some say it's science, some say it's a luck of the draw. I am a person of faith and to me, children no matter how they are, are all gifts from God. I know it sounds cheesy but I believe that God will not give us situations we cannot handle. And I personally believe that this applies to babies born with disabilities.