Tony was "an extremely lonely child with a talent for making things and a poor grasp of long-term consequences." His parents disappeared when he was younger; it is implied this is before he was a teenager, but is only specified as "a few years ago". They were "intending to be gone for a few days, and did not return." When he is twelve he uses his own DNA with a little bit of DNA from his Ditto, Mycroft, to create a clone of himself. This clone becomes his brother Sherlock, and they are thereafter essentially raised by Jarvis.