Generally speaking, children with sex chromosomes of XYY are unhealthy. Normally, a fetus has a pair of sex chromosomes, XX for females and XY for males. However, if the Y chromosome segregates abnormally during the second meiotic division during the formation of the father’s sperm, this may result in a fertilized embryo with sex chromosomes that are XYY, which is clinically one of the more common genetic diseases of sex chromosome aberrations. Children with XYY sex chromosomes tend to have no abnormalities in appearance and tend to be tall in adulthood. Patients occasionally see hypospadias, cryptorchidism, and testicular hypoplasia with disorders of the spermatogenic process and reduced fertility. Individuals will produce XYY offspring, but most patients can produce normal offspring. If the child’s sex chromosomes are found to be XYY during pregnancy testing, it is recommended that termination of pregnancy be considered.