Granted, even in such a family, some children do not suffer from those diseases, but they still may be carriers. Not so with sin.
صَحِيحٌ أَنَّهُ فِي عَائِلَةٍ كَهذِهِ لَا يُعَانِي جَمِيعُ ٱلْأَوْلَادِ مِنْ تِلْكَ ٱلْأَمْرَاضِ ،‏ إِلَّا أَنَّهُمْ قَدْ يَحْمِلُونَهَا .‏