Some biblical scholars and theologians think that Achan's sons and daughters were “brought out” only to be the spectators of their father's punishment, but most conclude that they were also put to death along with their father. God commanded that magistrates should not put the children to death for the sins of the fathers, but God did not intend to bind himself by this law. Therefore, God could justly command the execution of a whole household by divine credence. That said, it is entirely possible (and even likely) that Achan's sons and daughters aided and abetted their father in his sin.
Theology Applied