What If - Instead of being created by Ochanomizu, Astro's parents were "repurposed" into becoming part of his family - similar to Cobalt's origins in the original animation.
My impression is that Ethanol, Astro's Dad, was a robot test driver (which is probably a nicer way of saying he was a living test dummy) except he was specifically involved in testing some very special vehicles and equipment that were not meant for the general public. Even though he doesn't have much fighting experience or capabilities, his body was made specifically to handle any kind of rough damage and essentially walk it off after a short while and testing.
Meanwhile, Rin, Astro's Mom, did have official documentation - but all the information is either considered officially lost and whatever scraps are left are considered classified and the text blacked out. (Don't worry about it. It's probably nothing too serious 🤥). What does need to be stated is that she is incredibly strong and has a lot more power than she lets others believe and has A LOT more restraint than most robots.
This could also be why they're both immune to the power of the Blue Knight's sword.
This also makes for a interesting explanation for why every violent robot had every opportunity to go after Astro Boy's family's home - but chose not to, says something about his parents holding down the house.
And the the only times someone did take the opportunity to barge in and mess with their house, they were usually humans.
