Let's see, Hans Grosse is much larger than any other Nazi soldier, but this is also true of all the bosses in the game, with the exception of Hitler himself — height-wise — when Hitler's mechsuit is defeated. (Did Hitler gain a some weight?)
What partly inspired the idea for this WMG was the fact that in Episode 2 — the episode where one fights Dr. Schabbs himself — the pen-ultimate level has a grid-like maze with the doors to the next areas being blocks of walls that are "pushed". A few of the pathways lead to encounters with Hans Grosse, which might lead one to believe that the Doctor has been keeping some spare Grosses locked away for whatever reasons. The secret level of Episode 6 even has encounters with Hans as one of it's selling points, in addition to also reintroducing Dr. Schabbs's mutant soldiers.
Whether Doctor Schabbs had a hand in the family bloodline is still anybody's guess. Also, the maze seems more like Breaking the Fourth Wall of the storyline as Apogee had a special contest planned to see who could find the "correct" path through the maze. In the end, this is just a fun wild guess.
- The official hint book really messes this theory, as interesting as it is. The Hans clones that appear in the final episode's secret level are stated in the hint book to be Hans and Gretal's identical twin brothers. So while Schabbs may or may not have been involved with turning them into super soldiers, the blame on there being so many of them falls on Mr. and Mrs. Grosse.
- Likewise, the reason Dr. Schabbs has the highest hit points on Death Incarnate: He had developed a powerful next gen. Applied Phlebotinum and used it on himself to be ready for B.J. before their battle at the top of the castle. It was not enough and, B.J. filled him with a lot of bullets before terminating the research project.
- Obviously, he uses experimental UAC technology to store his weapons in an endless storage space.