Question

Is it possible for a human to only have one kidney as a birth defect?

Answer 1

no it is not possible

Answer 2

hey buddy
hope my answers explains all your queries
now the answer
as by birth normally all humans have 2 working kidney but in some rare case it is possible to have only one working and it works normal that condition is known as "kidney agenesis or renal agenesis" the quoted term means one kidney fails to form during the intrauterine life
other case is of kidney displasia in which both kidney are present but one of them is non functional ... The first case of renal agenesis is though rare but with it one can lead normal life with some precaution which can make more metabolic pressure on it hope it works