people say that asuma is possibly related to the 3rd since his last name is sarutobi.....
personally i think thats bull, since they wouldve at least HINTED at it during scenes like the funeral

but if that WAS the case, then konohomaru's dad might be asuma

otherwise i'd just assume he has parents somewhere.....there's alot of kids in the series that have parents you never see, but you can tell which ones dont have parents by the messed up beliefs and ideals they end up obtaining