Must be so difficult for the father. But he is right and good for him for having the courage to say it.
One bad seed in the family is believable. But the article says his brother has also joined the IS. Two bad seeds, no, something smells. Could be the father is smoozing the neighborhood.
I have always believed that the majority of Muslims in the west are good people. Not the vast majority perhaps, but a majority. Sadly, this means that they are not good Muslims. You can be one or the other. This guys son is just being true to the religion he received from his father.