The families that were torn asunder amid the Troubles in Northern Ireland
In the Northern Ireland Troubles such was the intensity of the conflict that sometimes even blood was not as thick as water.
Which in real terms meant that even brother would turn on brother, son would become an enemy of father in certain extreme circumstances.
The most infamous example of ideology transcending ties of blood was the curious case of Major Ronald Bunting and his errant son Ronnie.
The former was a unionist hardliner and ally of Ian Paisley who became notorious for participating in often violent counter-demonstrations against the civil rights movement.
Yet his son became an archetypal 68er, that post-war baby boomer generation who rebelled against their parents.
In West Germany, for instance, the 68ers reacted to the mums and dads that either actively took part or were silently supportive of the Nazi war machine by lurching to the far left, either in the street protests of student struggle or at its extreme terminus by joining the Red Army Faction/Baader Meinhoff terror group.
For 68ers like Ronnie Bunting junior their rebellion went from signing up to the civils rights movement or enlisting in hard left parties right all the way over to the open embrace of neo-terrorism, firstly with the Official IRA and later the INLA.
Brothers, too, could be divided by factionalism with one aligning themselves with the Officials in 1970 and the other the Provisionals. There are documented cases of brothers firing on each other and being part of killing squads targeting their siblings during the madness that was the mid-1970s.
Even in the loyalist paramilitary underworld there have been recorded examples of where family connections counted for nothing.
Possibly the most striking instance of this was when Johnny 'Mad Dog' Adair ordered the kneecapping of his own son Jonathan junior, aka 'Mad Pup', over an alleged misdemeanour the UDA's 'C' company had accused him of.
"Hard but fair," Adair senior half-joked when this writer challenged him about it many years later.
The Troubles and the social seizures they triggered not only tore communities but even families apart as brothers, sisters, fathers, mothers, uncles, aunts and cousins took different sides.
Yet, to return to the Buntings, perhaps it is worth remembering an iconic photograph republished in the book INLA: Deadly Divisions.
It captures Major Bunting at his son's funeral after Ronnie junior was shot dead by a UDA hit team, possibly with the aid of the security forces, in the autumn of 1980.
The image is a haunting one.
It shows the Major distraught, crushed and wiping a tear from his eye as his son is laid into the grave.
In death at least such ties of blood finally trumped the lure of conflicting ideologies.
- Henry McDonald is co-author of INLA: Deadly Divisions, published by Poolbeg Press