Janet, a 39-year-old mother of two, has recently been diagnosed with osteosarcoma (bone cancer). Her oncologist notes that Janet's father succumbed to brain cancer at the age of 45, and her younger sister has just finished treatment for breast cancer. Suspecting that Janet and her family have a hereditary condition that predisposes them to cancer, she suggests that the family undergo genetic testing. Results reveal a mutation in the TP53 gene, a tumor suppressor gene; this mutation, coupled with the family history of early-onset cancer, indicates Li-Fraumeni Syndrome. As Janet begins treatment, she is also confronted with the dilemma of whether to have her children, a 10-year-old daughter and 7-year-old son, tested for the TP53 mutation. What are the scientific and ethical arguments for and against genetic testing of children for predisposition to early-onset cancer?