1) Everyone calls him "Annie". If you're a bloke, and you were called Annie in front of everyone, wouldn't you want to be called Darth Vader and go and kill all of them ?
2) Forcibly removed from his mother by Liam Neeson. That must have some psychological effects on him - loss of a parent (unless he comes back for her in the next episode), loss of a feminine figure in his life. While I don't doubt Obi-Wan's character, he can't be much of a substitute for his mum.
3) The hint that he was born by immaculate conception. Again, the lack of a male role model from an early age may well lead him astray and susceptible to ideas from "bad people"