Geli Raubal, born in 1908, would have turned 18 in 1926. So it is not unreasonable that she would have become pregnant and given birth in 1928, the year Herlind Jentsch was born.
In 1929, Geli came to Munich to live in Uncle Adolf's apartment and attend University. Whether or not a child was also in the apartment is unclear, however in 1931 she did commit suicide. Was it connected with the 3rd birthday of Herlind a couple of months earlier, a child who had been fostered out to maintain appearances? Apparently she claimed that Adolf had some weird sexual practices, but this could well be related to Satanism and the Left-hand Magick that they practice which involves sexual frenzy often involving masturbation and or anal intercourse.
Also attached is the original photo, before the image was repaired. Some have claimed this is a boy, mistaking the fabric shorts for lederhosen. If the feminine features and long hair (not worn by boys in Hitler's Germany) do not convince you, the girls shoes should do it.