KILLER KIN

Brussels Terrorist Brothers: Why Does Jihad Run in the Family?

Six of the 19 9/11 hijackers were brothers. The Tsarnaevs blew up the Boston Marathon. The Kouachis shot up Charlie Hebdo. And now the Bakraouis have terrorized Brussels.

03.24.16 5:00 AM ET

Brussels attack brothers Ibrahim and Khalid El Bakraoui join a long line of terrorist siblings, and they won’t be the last.

Particularly in groups bound by ethnicity or religion, it is common for members of the same family to become involved in the organization. From the perspective of the terrorist group, engaging family members can help sustain both the commitment of participants as well as increase the likelihood of strong operational security.

Many siblings are recruited into terrorist groups together, with the older sibling often facilitating the entry of the younger family member. British twin sisters Zahra and Salma Halane, for example, arrived in Syria in 2014 and proceeded to try to recruit their younger siblings to join them. We observed this phenomenon during the Charlie Hebdo attacks in Paris by the Kouachi brothers and, at the Boston Marathon, by the Tsarnaev brothers.

Statistics prove that is not simply a random phenomenon. Six of the 19 hijackers on 9/11 were brothers, and according to the research of Mohammed Hafez, as many as 25 to 30 percent of cases of terrorist acts involve members of the same family. Research from the New American Foundation showed that a third of Western foreign fighters had family connections.

When siblings join terrorist groups, they typically are deployed together in the same operation, although occasionally at different locations. That appears to have been the case with the Bakraoui brothers in Belgium, and it also occurred in Russia in 2004 with Amanta Nagayeva, a Chechen woman who detonated herself onboard Volga-AviaExpress Flight 1303 from Moscow to Volgograd on Aug. 24, killing everyone on board. Her sister Rosa killed herself and 10 others outside the Rizhskaya subway station in Moscow within a week.

In cases of sibling suicide bombers, each sibling ensures that the other is less likely to change their mind at the last minute, or worse, inform on the group to the authorities. Terrorist organizations constantly fear infiltration. In interviews conducted in Northern Ireland with former members of both Republican and Loyalist terrorist groups, we were told that the terrorists spent almost as much time looking for potential spies as they did planning operations. Engaging siblings decreases the possibility of police or security services’ infiltration. We can assume that is the case for many groups that worry about the police, army, or security services infiltrating them.

Hafez also has observed that the recent heightened security environments encourage jihadis to turn to the family for recruits. “Kinship recruitment, which is difficult for security agencies to observe, is facilitated by several psychological mechanisms that bind individuals together on the path to extremism,” he wrote. Psychologically, high-risk missions require trust and commitment, which generally can be assumed when members of the same family operate (and kill) together.

Much like the echo chamber created within friendship networks—the “group of guys phenomenon,” as Marc Sageman has called it—an echo chamber can exist within the family. It is also possible that when an entire community feels disaffected, or marginalized, brothers or sisters will have comparable experiences and can be radicalized by some of the same influences.

However, similar experiences and backgrounds do not guarantee the same outcome. While many siblings followed the path together into terrorism, other families had opposite experiences. In the provisional IRA, it was not uncommon for one brother to join the IRA while his sibling became a Catholic priest. One Palestinian family had even more dramatic results: In 1981, Fathi Shiqaqi founded the Palestinian Islamic Jihad. His brother Khalil got a Ph.D. in political science and heads the Palestinian center for policy and survey research, and is a fellow at Brandeis University.

While brothers and sisters may be involved, and there are significant reasons why terrorist groups like to use them in attacks, it is important to emphasize that at the end of the day, people choose their own individual path toward or away from terrorist violence.

Yet in some cases, it has even become standard practice for groups that terror stays within the family. Our research has uncovered not just brothers, but sisters, cousins, and even parents and children who join the terrorist organizations as family units. ISIS has capitalized on recruiting entire families. Often the Muhajiroun (foreign fighter) father and mother will take their children along with them to emigrate to the so-called Islamic State. ISIS has been exceptionally good at convincing parents to come and bring the children in its video propaganda (Eid Mubarak from the Islamic Caliphate, 2014) and getting parents to allow them access to the children for training in their child units, the Ashbal (Cubs) of the Caliphate.

During the course of our research on ISIS propaganda and the recruitment of children, we have documented a father bidding his son farewell before a suicide attack, and 4-year-old Isa—son of U.K. jihadi bride Khadijah Dare—detonating a vehicle with three ISIS hostages locked inside. Australian Jihadi Khaled Sharrouf posted a photo of his 7-year-old son holding a severed head onto his Facebook page in 2014.

The fact that ISIS has deliberately recruited entire families means that the likelihood of seeing more such cases in the future are high. As families emigrate to Raqqa together and the children are exposed to extreme barbarism and atrocities, there will be more sibling children from which ISIS can and will recruit, as well as more family terror ties between parents and children.