While tucking our sons into bed the other night, I was struck by how many of their physical attributes they've inherited from my husband and me. Eleven-year-old Nate has my heart-shaped face, large eyes, and cowlicky hair, along with my husband's mouth and freckles. Six-year-old Nicky, on the other hand, has the same green eyes and dirty-blond hair that I do, but my husband's nose and chin. But those aren't the only things we've passed on: Nate has acquired my propensity for headaches and hay fever, and Nicky got my husband's eczema in a bad way. Of course, many chronic conditions run in families, but family history alone doesn't guarantee that a child will develop one of them. Instead, it signals increased risk. "Usually, it's a combination of genetics and environmental influences that triggers a condition," says Jennifer Shu, M.D., a pediatrician in Atlanta and coauthor of Heading Home With Your Newborn. You can't change your kid's genes, but you can get familiar with a few of the most common health problems that affect families and learn how to protect yours:

Vision Problems

will the kids get them? Your child's view of the world could be quite similar to yours -- literally. Nearsightedness, color blindness, and lazy eye (amblyopia) are often inherited, says Stuart Dankner, M.D., a pediatric ophthalmologist in Baltimore. If both parents are nearsighted, a child has a 25 to 50 percent chance. "Only females carry and transmit the gene for color blindness, but usually only males have the condition," Dr. Dankner explains. If the mother is a carrier of the gene, there's a 50 percent chance her son will have it.

signs they got nabbed: If your child complains of headaches, or often squints or tears up, especially with reading, watching TV, or at the end of the school day, it's worth having her vision checked. Children may not complain about nearsightedness until they're school-age, but it can be detected as early as age 3, says Dr. Dankner. That's when Crystal Smith's son, Cameron, began squinting to see things. "I knew there was a strong chance he'd have vision problems because my grandmother, aunts, mother, and I all wear glasses, but I didn't expect it to happen so young," says Smith, of Plainfield, NJ. Lazy eye can emerge during the first year, but it can be difficult to catch unless the pediatrician screens for it. Don't worry too much if your infant's eyes cross now and then -- almost all kids' do in the first couple of months; if you notice crossing along with a difference in pupil size after that, schedule an exam. As for color blindness, you'll usually know by age 5.

what you can do: If eye problems run in your family (and actually, even if they don't), it's smart to start regular eye exams with a pediatric optometrist or ophthalmologist by age 1. This is especially important if your family history includes needing glasses at a young age or if you suspect lazy eye at any time. Early detection and correction of vision problems can help a child feel and function at her best -- and, in the case of lazy eye, which can lead to severely impaired vision if untreated, it could even save her sight.

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