A gṛhastha will produce such good children and will give them to the society. Then, it will be a nice Krishna-conscious society. Only the gṛhastha will do such a thing. Therefore, it is the gṛhastha’s duty. The vaiṣṇava-gṛhastha, only for that purpose, will produce children. Otherwise, no need of producing a child, no need of accepting a wife, and no need for such marriage.