Yes, he was in the Hitler Youth. But to be fair all German boys were in it. It was compulsory I think. And actually quite a lot of German girls were in it too. My dad has a friend who was in the Hitler Youth and she says it was a bit like being in the scouts or something like that. They had no idea what it meant and she certainly didn't go around killing people or even hurting them. No one in the pope's immediate family actually joined the Nazis according to the reports on the internet. They were Catholics and the Catholics were being persecuted themselves.
Funny isn't it after the war you couldn't find a nazi anywhere, and anyway they were all harmless like the boy scouts ... what a lot of old apologist guff. Blimey even Basil Fawlty saw through that one. As to the Catholics being persecuted, where did you dig that factual nonsense up from? I think you may be confusing Catholic with other religious groups who were really persecuted (and actaully exterminated) by the German Nazis, not least the Jews and Jehovah Witnesses
The German population (and wider German speakers) was right behind the evil Nazi regime, they couldn't have sustained the war without that backing, and with around half the German population being Catholic, they have to stand up and take their share of the blame, and recriminations.