Hitler's father was quite cosmopolitan. He had a nationalist history teacher and a rough time after he was rejected from art school. Take that with a huge grain of salt since this is how he depicts it in his autobiography. I think the major part of his radicalization was in prison while he wrote Mein Kampf but that's just my opinion.
He was an intelligence agent assigned to infiltrate the German workers party, precursor to the nazi party. It’s the first bit in the “entry into politics section”.