I am quite sure that that is not who you think it is, just someone from that time period with a very similar hairstyle. A great-grandfather would be my guess.
Step 3: ask Yourself what are the odds that someone has a doppelganger Hitler grandfather
Step 4: ask Yourself who in their right fucking mind would put a picture/ portrait of their grandfather if he looked just like Hitler..
Step 5: ask yourself; why would a grandfather who looked just like Hitler; why would he give himself that hairstyle and give himself that mustache ... Grandfather must have heard of Hitler... no ?
Ok, so let me tell You something about Hitler ... He did lots of drugs, he aged and he obviously had different disease. Sooo; he looked a bit different year to year.
Now let me tell You something about portraits; they're made by different people and they don't always look on point or alike.
Took me a lap around the picture. "Hmm, let's see. Curtains, normal hands, picture of Hitler, blond girl looks normal, nothing weird in the shelves..."