I see your point. But I believe people would only blame parents when the kids are young. Not when they have matured in adulthood. Because adults ought to know better.
Back to this case, religion has done nothing for this muslim family. They might as well not subscribe to Islam.
Adults ought to know better? But when in desperation, they can also commit crimes. They can also steal, lie etc. They are not perfect. But not the faults of religion. Back to this case. I dont know whether they are practising Muslims. I cant judge them. Only God. But in this world,they have to face the punishment meted out.