Here's a run-down of the basics: The biggest stone in Hitler's shoe was the First World War, or more specifically, Germany's losing of the war. Hitler wrote his motivations in Mein Kampf ("My Struggle" - Hitler's manifesto, which he wrote in prison) and said that all the problems of Germany were the result of Jews making plans to harm Germany. He said that it was Jewish & Communist politicians who planned the Armistice of 1918 that ended the war, and who allowed Germany to pay huge reparations - large amounts of money and goods - to the other nations. This ruined Germany's economy, and the political instability in the country was a ripe Petri dish perfect for someone like Hitler to come to power. Not only that, but Hitler had been a soldier during this war and had fought hard. Like all Germans, he said that they had been 'stabbed in the back' (let down by their weak government) and that Germany shouldn't have surrendered.

Edit: I'm not sure about his parents being an influence, that's something I'll do a little research on.

Hitler was influenced by the pan-German idea of a unified state of all German-speaking people as well as by the rampant antisemitism, both religous in nature, as expressed by catholic politians like Georg Ritter von Schönerer and racial, like Jörg Lanz von Liebenfels, who published a crude mixture of occultism, politics and racism to name just a few.