Having a child with an XYY chromosome is generally not recommended. Babies with chromosome XYY may develop XYY syndrome, therefore, it is generally not recommended to have a baby when it is detected to be genetically XYY. People with XYY syndrome have underdeveloped testes, impaired spermatogenesis and reduced fertility. Hypospadias, etc., and occasionally cryptorchidism are seen. However, most male patients are fertile. Patients with multiple Y’s have mental retardation and multiple congenital defects, and boys born to fertile individuals will have a 1/2 risk of developing the disease. Therefore, when the baby’s sex chromosome is detected as XYY, the pregnant woman is usually advised to terminate the pregnancy. And if the couple wants to get pregnant again, chromosome testing is recommended in advance. If in doubt, seek medical advice as early as possible.