I thought you guys might find this interesting, since the Androids are coming up. It's from a Toriyama interview from the manga:
"The model for No. 16 was Dr. Gero’s son, who died young long ago. He was a high-ranking soldier in the Red Ribbon Army, but he was felled by an enemy bullet. Having a special place in his heart for his own child, Gero gave No. 16 great power and a fearsome explosive mechanism1, but not wanting him to be destroyed in battle if possible, he gave him a gentle personality, which caused No. 16 to become a failure."
"The model for No. 19 was a doll that was displayed in the command center of an enemy base. Way back when, Dr. Gero took it back with him as a war trophy."
"The sole weakness of the genius Dr. Gero’s inventions was that “personality control” didn’t work well, so that’s believed to be the reason why he changed his methods to using humans who were bad to begin with and remodeling them into Artificial Humans, like Nos. 17 and 18. It was thought that he had succeeded with cyborg-types, but ultimately, these were also failures because they wouldn’t listen to orders the way he wanted. He reversed course again, and No. 19 was his first success."