His worst fears were confirmed when one uncle, Heinrich Schendel, was among 10 people convicted in Italy in absentia in 2005 of one of the worst civilian massacres in Western Europe in World War Two.
As the Nazis retreated in northern Italy in August 1944, the SS 16th Division murdered 560 civilians, including more than 130 children at Sant'Anna di Stazzema in the Tuscan hills. Not one of the 10 found guilty was ever extradited.
Heinrich Schendel and his family always denied his part in the massacre. But when he died last year, his nephew decided to act.
"I somehow had to break the silence in the family. I stumbled across the story of Enrico Pieri, a boy who got away and hid in a bean field after his sisters and parents were killed," says Andreas, a Dresden-based self-defence instructor and writer.  "Somehow I figured Enrico would be the one to talk to."
He contacted Enrico Pieri, now 81, and ultimately they agreed that Andreas should travel to Italy for a meeting.
One of the few remaining survivors of the massacre, Enrico drives up to his old village in the Tuscan hills several times a week. Apart from a museum and a national peace park, Sant'Anna is largely deserted and his parents' old house abandoned.
Outside the house, the persimmon trees planted during the early years of the war still bear fruit every winter.
But the only habitable room is the kitchen, where his entire family and another family were murdered in front of him.
He only survived because a girl from the other family dragged him into a stair cupboard. "In my house it was all very brief, when the Germans came it lasted a maximum of 30 minutes".
Enrico has agreed to meet Andreas Schendel at a youth peace festival but the two men decide to have an initial, private encounter at the village church. In front of this small building 130 people were slaughtered and their bodies set alight.
"We hugged, and I was surprised and relieved, but afterwards when we said goodbye we could only shake hands," Enrico says. "That made me realise there is this wound and it's not going to heal."
Inside the church, Andreas Schendel broke down as he saw the pictures of the child victims.
The pain of the meeting was too great for Enrico Pieri, who shrugs and says quietly "it's difficult".
Sharing a stage later with Andreas in front of a group of teenagers, his face lights up as he speaks passionately about European unity and reconciliation with modern Germany. But the expected handshake only takes place afterwards when prompted by photographers.
"This man is a saint because he is able to forgive the Germans as a public, and that's all a saint can do," Andreas says as he reflects on his meeting with Enrico Pieri. "But to forgive my uncle, that's not the question."
"The 16th SS Division was one of the most ruthless units in the Germany army of the Second World War," says Carlo Gentile, who served on a joint German-Italian commission investigating the Nazi occupation of Italy. "They killed 2,200 to 2,500 civilians in August, September and October", operating a scorched earth policy as they retreated north ahead of the Allies' advance.
No clear reason for the Sant'Anna massacre has been given. One theory is that it was a reprisal for a partisan ambush on the unit four days earlier, a short distance away at Farnocchia. Former partisans say they were not present in the village, as they had been told by the Allies to leave.
Some of the more seasoned members of the division had been concentration camp guards in the SS Totenkopf (death's head) Division and some had been involved in wiping out the Warsaw ghetto.
Schendel was one of the division's less experienced soldiers.
Word of Andreas's visit has reached other survivors, now mostly in their late 70s or 80s.
Licia and her two sisters Adele and Siria lost their mother and two other sisters, including 20-day-old Anna Pardini, the youngest victim of the massacre.
"I don't know if it is a good thing or not that he comes here," Licia says, as the sisters lay red roses at the hilltop memorial, where the remains of every victim have been buried. "If he wants to be here, we will listen to his story."
Another survivor, Romano Beretti, points out that, as the son of one of the killer's brothers, Andreas Schendel bears no personal responsibility for the massacre.
But Mr Beretti chooses not to make the painful decision to meet him. The sisters are there, and so is survivor Enio Mancini, who along with Enrico Pieri has for decades fought for justice and only achieved a symbolic Italian verdict.
The sisters sit quietly, listening to Enio and Enrico, who between them have battled to keep the memory of Sant'Anna di Stazzema alive.
"We didn't want revenge, we wanted justice," Enio Mancini tells the teenagers. "What makes me angry is that these 10 officers who were convicted lived their lives as if nothing happened."
Later he gives Andreas a hug and the three men stand together.
On top of the hill above Sant'Anna, a memorial contains the remains of all the civilians murdered on 12 August 1944. Alongside the names of his family, Enrico Pieri has added his own name and those of his wife and son.
While none of the survivors remained at Sant'Anna, they still live close by, their lives always overshadowed by the hill on which their families were killed.
And it is the youngest whose memories are clearest. "It seems odd but I can easily forget something that happened maybe a couple of days ago, but I can't forget what happened here during the war," says Romano Beretti, who was just seven at the time.
Allied courts set up after the war convicted SS general commander Max Simon of the massacre at Sant'Anna. But another SS commander, Walter Reder, was acquitted in 1951. He was, however, jailed for the Marzabotto massacre a few weeks later in which 770 civilians were murdered.
Then, for 40 years there was silence until, in 1994, 695 Allied inquiry files were discovered in Rome, locked away in what became known as the "cabinet of shame", and the quest for justice resumed.
After extensive investigation, 10 Germans were put on trial in absentia and convicted in June 2005:
But none was extradited and last month a court in Hamburg ruled that Gerhard Sommer, 93, had dementia and was unfit to stand trial.
"Until 2002, the German authorities did absolutely nothing to investigate the war crimes at Sant'Anna," says lawyer Gabriele Heinecke, who has fought for justice for Nazi victims in Italy and Greece. "The prosecutors and judges of the young Federal Republic of Germany were former Nazis in the majority. They had no interest in pursuing action in which they were themselves ultimately liable."
And as the perpetrators have gradually died out in the past decade, investigator and historian Carlo Gentile argues the justice department in Stuttgart could have worked far faster. "I find it hard to believe that there was no intention to slow things up. I have no proof of that, but the facts were already known and I can understand people's frustration."
Andreas Schendel always knew violence was endemic in his family and any talk of the war was off-limits, as two of his uncles had served in the Waffen SS.