this is where u are wrong it is very normal 4 a child to explore their genital region and if it feels good to them they will continue to do so it is important to talk to them, ask them y they are doing so and to gently tell them that it is a private thing and should be so so in the privacy of their room or the bathroom when they are alone but not to alarm them as that could raise some issues latter on in life
this is an old thread that has been dragged up.,no it is not normal at a very young age it ius a learned behavior many children have been abused .Compulsively tells you to seek help ...
Usually kids will "find" thier privates and explore a bit around age 4-5. If you don't make a big deal of it, and remind him that touching his privates needs to be done in a private place, eventually he'll quit. Hope this helps. Good luck and God bless.