Your father could be having acquired cystic kidney disease which develops as one ages.Or they may be due to Familial cystic kidney disease (ADPKD) in case if there is history of cystic kidney disease in family. In either of the cases do some basic investigations like urine routine, serum creatinine
Just control of Hypertension
,prevention of urinary stone
formation and urinary infection by drinking adequate water is the only thing required.Familial members need to be screened by sonography
for kidney cysts. Anyways consult your Doctor for detailed evaluation and Treatment.