Counterterrorism

BRUSSELS ATTACKS: WHY DO FAMILY MEMBERS COMMIT EXTREMIST ACTS TOGETHER?

It appears to be increasingly common that terrorist attacks not of the lone-wolf variety involve members of the same family.

Some of them, like the San Bernardino attack last December, are committed by married couples or romantic partners.

But quite a few recent terrorist atrocities—the Charlie Hebdo attack, the Boston Marathon bombings and now Tuesday’s Brussels attacks—have been perpetrated by siblings. So is there a link between within-family radicalization and acts of terrorism? And is terrorism different from any other crime in this respect?

Family ties and the militant extremist mindset

Both genetics and environment are known to influence criminal behaviour. But the exact nature of these influences and their relative importance are still being debated.

It can be expected, therefore, that genes contribute to terrorist behaviour. But it is wrong to conclude that just because two individuals have a common genetic make-up, one will follow the other if the other becomes a terrorist. Instances of only one family member displaying criminal behaviour are very common.

Nevertheless, there may be environmental factors that contribute to and interact with genetics to cause terrorist behaviour. If so, one would expect to find more terrorist acts than other kinds of criminal acts committed by members of the same family. Family members share both genetics and environment to a greater extent than people in general.