I prefer the adage....."Shit happens!"
Prefer my version of that. "Shit happens. Then you flush."
As to whether God should get the blame: Or the surface, yes. It's surely not beyond his power to give a defective sperm a nudge out of the way at the right instant. Bit rough on not only the kid but the parents too, that he doesn't bother. It's not so long ago that genetic defects were considered punishment from God on the parents.
However, everything has a reason. Matthew 25:40: The King will reply, 'Truly I tell you, whatever you did for one of the least of these brothers and sisters of mine, you did for me.'
God and Jesus are both pretty down on people who talk the talk but don't do the walk. You know the sort, they are all too common. Pass a beggar in the street and tell him to get a job, then walk into the church and feel good about themselves.
In counterbalance, most people with genetic disorders seem to be happy. Of course, they have moods, same as everyone, but their default state is cheerful and loving for the most part.