Communism, like any system of control, was based in part on coercion. Millions died in the purges of Lenin and Stalin, guilty and innocent alike, creating a political climate in which fear silenced dissent. In later years the punishments degraded to 'mere' imprisonment, beatings, harassment, and loss of work, but the basic principle was the same: obey, or bad things happen to you.
But the Communists found something rather odd. Despite all the fear that they could create, there were still those who would not conform. They could be killed--and millions were--but Stalin's successors lacked his capacity for genocide. They could be imprisoned--and millions were--but still they resisted. The threat--even when carried out--proved insufficient to coerce obedience. People remained willing to sacrifice themselves to defy the system.
So they came up with a new threat. They went after the families--children, spouses, relatives. There is a moment in the film 'The Lives of Others' wherein a neighbor witnesses a wiretap, and is subsequently caught doing so. Knocking on her door, the security agent threatens not her, but her daughter. This was--like so much else in the movie--an accurate portrayal of life under communism.
Humans are programmed for acts of bravery and defiance. The rebel standing up to authority, the spear-armed hunter standing down a lion, the soldier or the patriot risking their life for what they believe. This is part of who we are, part of what's best in us, and the communists couldn't stamp it out of people. No matter how many they killed, imprisoned, starved, or beat, defiance remained because it is an integral part of human nature.
For those who possess such traits in sufficient qualities to defy communism, however, sacrificing others--especially those that they cared deeply about--was not. A noble spirit might defy a totalitarian system no matter what the threat to itself, because such a spirit cares about other things more than it cares about itself. So the Communists threatened those other things. Families of defectors were jailed. Children of dissidents lost opportunities for employment and education. It was a system of punishment far more insidious--and more effective--than mere coercion, and one of the most evil things that the Communists did.
Why do I bring this up? Oh, no real reason.