You all keep acting like 9 months is a year. Yes, it is CLOSE to a year but if if Goten in conceived within those ten days or right before the andriods (cause I dunno how Goku and Chichi could get away from Roshi during the 10 days) then Chichi wouldn't look pregnant or possibly even know yet. Then 9 months later Goten is born, it'll still be in the year Cell came. So it would be possible for Goten to be 7 at the start of the Buu Saga, maybe just in his younger 7's.