QuestionIf a boy only has one testicle, what should be happening in the future?
Having only one testicle will not make much difference in a man's life. He will still be able to have children, though it might take longer for his wife to get pregnant. This is because pregnancy is based on chance and a man with one testicle will have fewer sperm cells in each ejaculation. It won't be so low that pregnancy won't happen, but perhaps low enough to decrease the odds of a pregnancy happening by a small amount.
It won't effect his hormone levels. When there is only one testicle, it makes up for the absence of the other one by putting out more hormones.
He should be extra careful when playing sports to protect his last testicle since he doesn't have a backup. So wearing a jock strap and cup would be critical.