The horrific Islamic State-linked terrorist attacks in Paris in November 2015 illustrated another troubling reality: family-affiliated terrorism. More specifically, French nationals and brothers Ibrahim and Salah Abdeslam participated in carrying out the attacks, with the former conducting a suicide bombing at a Paris restaurant, and the latter renting a car that delivered attackers to Bataclan concert hall.

Now an international fugitive, Salah previously served time in prison for armed robbery with the mastermind of the Paris attacks Belgian Abdelhamid Abaaoud. During a police raid in Paris later that month, Abaaoud was killed with his cousin, Hasna Ait Boulahcen. Aitboulahcen and Abaaoud were killed during a standoff with police.  Prior to his demise, Abaaoud recruited his 13-year-old brother to join the Islamic State.

In the United States – as internationally – families have been enticed by Islamic State propaganda. For instance, late last year a Mississippi couple (Jaelyn Delshaun Young and Muhammad Oda Dakhlalla), a Texas family (Wolfe) comprising a husband, wife, and their children, and three Illinois siblings (Khan), including two minors, were detained at different airports while trying to join the self-declared caliphate.

Likewise, in 2015, brothers Alaa and Nader Saadeh, as well as three others, allegedly conspired to travel to Syria and join the Islamic State. Last year, German authorities intercepted two Colorado teenage sisters and their female schoolmate after they arrived at Frankfurt Airport en route to Turkey while intending to reach the Islamic State. Last March two Illinois cousins (Hasan and Jonas Edmonds) were arrested for allegedly planning to travel to Syria and join the caliphate (Hasan). Jonas intended to kill more than 100 people while conducting a terror attack against the Joliet Armory.

Other noteworthy terrorists in this family-linked milieu include Charlie Hebdomagazine assassins Cherif and Said Kouachi, Boston Marathon bombers Tamerlan and Dzhokhar Tsarnaev, and three sets of brothers who served as hijackers on 9/11. There are numerous frameworks by which to analyze the prevalence of extremist/terrorists in family units.

This type of deviancy, occurring within the rubric of social networks, is not new. Terrorism within family units is a manifestation that has occurred throughout the world. The full spectrums of familial relations have been witnessed in this form of political extremism.

Such radicalization has materialized across diverse political ideologies. Family frameworks enable higher instances of conversion to radical beliefs given the imprimatur of credibility and trust that attach there versus unaffiliated networks.

A broad variance has been observed regarding the backgrounds of the family members, such as: socio-economic, race, religion, ethnicity, national origin, and foreign-affinity-links. Family participation in terrorism pervades hierarchical and networked structures as well as unaffiliated cabals. Such kin-linked terrorism comprises different levels of group participation and types of terror attacks.

Patriarchs tend to have a strong influence on radicalizing and recruiting family members to the cause. Widows and other female survivors of their kin perceived as victims of state oppression sometimes, too, embrace violence. Most prominently is the case of the Black Widows of Chechnya.

Threats arising from family-connected terrorism must be understood and undermined, whether aligned with the Islamic State, al Qaeda, or other terrorist groups. The November 2015 Paris attacks, as the Charlie Hebdo, Boston Marathon, and September 11 terror incidents before, are bloody reminders of this terror phenomenon.

In December 2015, 14 people were killed, and 21 others injured in San Bernardino, California, during the rampage of husband and wife, Syed Rizwan Farook and Tashfeen Malik, respectively. The shootings increasingly look like terrorism as apparently Malik pledged allegiance to ISIS through Facebook before the pair undertook the attack. And so, sadly, family-affiliated political violence will likely continue for many years to come.