What I'm intereseted in knowing is : What type of image of his son did they carry to their grave? Was it the nobody who gave it a shot in politics? The sensible kid who wanted to paint? The political and spiritual leader of an entire people?
Hitler's father Alois died in 1903 at the age of 65, his mother Klara Polzi died in 1907 at age 47.
Hitler's parents both died before the start of WW1, and before he was 18.
His parents had little to no reflection on his political life since they weren't alive. He and his father developed a strong antagonism with each other. Hitler's dream in his formative teenage years was to become an artist. His father actively attempted to suppress this by sending him to technical school instead. Hitler reveals in Mein Kampf that he actually was "throwing the fight" in school in hopes that his father would give up and let him follow his dream.
Hitler formed most of his anti-semitism about the time his mother died, although strong German nationalism was present in his earlier life. There is still debate when he first expressed antisemitism ranging from when he left Linz to after WWI. General consensus now centers on general paranoia resulting from the unfavorable German exit from WWI to account for the crystallization of his ideas.
He was the fourth of six children, his older siblings died in infancy.
In Sept 1931 his half-niece Geli Raubal committed suicide with Hitler's gun in his Munich apartment. There were rumors of a romantic relationship between them.
Paula Hitler his youngest sister died in 1960 at the age of 64. She lived in seclusion after the war. In 1959 she agreed to be interviewed by Peter Morely. Between 1930 and 1945 she received assistance from her brother and lived under the assumed name Wolf at Hitler's request.
His final remaining sibling Angela was a half sister from a previous marriage of his father and she died in 1949. Hitler remarked that he regarded both of his sisters as "stupid geese". Both of his sisters made statements after the war that they didn't believe that their brother could have known anything about the Holocaust.
You can find all of this information from various wikipedia articles but a prime reference of Hitler's are:
"The Mind of Adolf Hitler" by Lange
"Hitler:Legend, Myth, Reality" by Lane