Hi, I had gone through your question and understand your concerns. You should be worried but not too much. Half of 47,XYY boys identified by newborn screening programs had learning difficulties—a higher proportion than found among siblings and above-average-IQ control groups. They had high height,not evidence with cancer. XXY is sign Klinefelter syndrome. Men with Klinefelter syndrome do not have an increased overall risk of acquiring malignant neoplasias. However, they have an increased incidence of breast cancer and extragonadal germ-cell tumors mostly localized in the mediastinum. Breast cancer occurs rather late in life, whereas germ-cell tumors appear mostly before the patient reaches the age of 30 years. Prostate Cancer is reduce. You have just mosaic form, your risk is less in 2 times. Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. I will be happy to answer your questions. Wishing you good health.