if it's just static electricity once you get the discharge it would be over and you wouldn't feel it again unless you are constantly rubbing your feet on the carpet while playing
Is this something you feel constantly using the guitar ? Some people are more sensitive to voltage than others which may be why your dad doesn't notice it. Stray voltage is something that some are more sensitive to than others, happens in swimming pools that are not properly bonded/grounded and some notice it and some don't.
Also you mentioned 5 volts are you using a multi-meter or something, what exactly are you measuring to ground, your guitar strings are reading 5 volts to ground ? This may turn out to be nothing but generally when your guitar is showing a voltage to ground I would treat it as a sign that something is wrong and get it checked out, better safe than sorry.