Hereditary Risk: Medium
Most Vulnerable: Children who have a family history of melanoma, the form of skin cancer that's the least common, but the most deadly. If one parent has had melanoma, a child's risk doubles to 3 percent. If both parents have had it, the risk is about 5 to 8 percent. Risk is even higher if a parent or close relative was diagnosed before age 50. Basal-cell carcinoma, the most common type of skin cancer, is not genetic. However, blonds and redheads with light eyes are at increased risk because they tend to have fair skin without much natural sun protection.
Best Defenses: Protect your child from the sun. "Even though this disease doesn't strike until adulthood, about 80 percent of cancer-causing skin damage happens before age 18," says Dr. Bachman. It's important to apply broad-spectrum sunscreen with an SPF of 15 or higher every time your child goes outside (even on cloudy days)--especially if melanoma runs in your family--and make sure he wears a wide-brimmed hat or visor. A recent study found that kids who wear sunscreen regularly actually develop fewer moles, which can become malignant. It's also wise to follow the shadow rule: If your child's shadow is shorter than he is tall, the sun's rays are too strong and it's time to play in the shade.