Last Friday in the Times of Oman, there was a story about a father in Pakistan who disowned his son for joining the Taliban and fighting for them. A month earlier, the Daily Mail shared online a story of another father whose son had joined ISIS( and the son was even shown in a recruiting video for ISIS recently). This father banned his son's photograph's from his home until the "brainwashed" young man would turn from his ways or be treated. In the meantime, that father is apparently disowning his son.
I had noted some years ago in my Middle East experiences that fathers were often extremely lenient and forgiving of their children's sins and bad or horrible actions. These fathers would allow their sons for example to abuse the family car and even kill others with the car through their driving negligence--while the father would never consider kicking the son out of the family home. This reticence to do anything to imply disowning one's son was surprising to me because I felt it showed a bias toward family over one's faith.
Therefore, this current trend in the Islamic world for a "father to disown his own son" for going off to fight a war or deciding to join a terrorist group intrigues me. With this growing curiosity in the apparent rise in Islamic parents disowning their children for joining the Taliban or ISIS in mind, I decided to look up on the internet what is exactly described in terms of disowning children who reject their parents demands or wishes.
I found the following which should prove enlightening to many:
The Parent's Consent is needed for Jihad
"Pleasing one's parents is considered so important in Islam that the son is forbidden to volunteer for jihad without his parent's permission, in spite of the fact that fighting in the cause of Allah (jihad fi sabeel Allah) has such great merit in Islam that the merit of a person who spends his nights in prayer and his days in fasting falls short of it. According to Islamic tradition, "A man came to the Prophet (peace be on him) and asked his permission to go for jihad. The Prophet (peace be on him) asked, 'Are your parents living?' 'Yes,' he replied. The Prophet (peace be on him) then said, 'Then strive in their service,'"
On this ground alone, it appears that if the son knowingly rejects his father's position on a jihad, he is already providing grounds for being disowned by the parent. Moreover, the following is also to be understood. One of the three major sins in Islam is to disobey one's parents.
Disobedience to Parents: A Major Sin
Of the "Three persons [who]shall not enter the Garden [of Paradise]" is "the one who is disobedient to his parents". In addition, "Allah defers (the punishment of) all sins to the Day of Resurrection excepting disobedience to parents, for which Allah punishes the sinner in this life before his death."
In other words, it appears that a parent and his family are permitted to punish the offspring who goes off to fight a war or join a terrorist group in opposition to one's parents. This would include the act of disowning one's own child.
 The Parent's Consent is needed for Jihad, http://www.themodernreligion.com/family/children_rights.htm
 Disobedience to Parents: A Major Sin http://www.themodernreligion.com/family/children_rights.htm