Fauna's right, Tonigirl1000, Reno was an orphan who was taken in by the Robot Circus as a baby. They raised him from an infant and he pretended to be a robot, so he could perform with them and no humans would be the wiser.
Hope that's been of help.
Yeah, even with the bad Narutoish voice and the stupid "Let's Rocket" catchphrase, I was still saddened watching him suffer like that. Goes to show just how powerful a character Astro can be. I can't imagine how i'd be if I heard his Japanese voice go through this