Hello, As far as kidney stones are concerned, that is not an obstacle in donating or receiving a kidney. It is just that that if the stones are in kidney itself, then the receiver will have to pass them in urine by drinking lots of fluids. As for the half brother question, a kidney transplant requires immense matching and cross-matching of blood, tissue, antibody etc and tests are also performed to check for diseases that can be transmitted to the receiver. In addition to that, urine tests, radiologic testing and cancer screenings are performed. If all these test reports indicate compatibility between the donor and the recipient, then the kidney can be transplanted. In addition, as they are half brothers, there are more chances that they will be compatible for kidney transplant than transplant between two stangers as they do share one parent and so some genetics. I hope this information is helpful to you. Thank you for using HealthcareMagic. Take care. Best, Dr. Viraj Shah