How can a man father children without disability?

Islam seeks to increase the Muslim nation by encouraging marriage and procreation, as the Prophet, peace and blessings be upon him, said: "Marry the affectionate, fertile woman, for I will boast of your numbers before the nations." The means of procreation is marriage if a person is naturally healthy and sound. If not, then he must consult a specialized doctor, for the Prophet, peace and blessings be upon him, said: "Seek treatment, for Allah, the Almighty and All-Glorious, has not created a disease without creating a cure for it, except for one disease: old age."