One of parenthood's most daunting responsibilities is making medical decisions knowing they might affect your child for the rest of his life. While some decisions -- should we put a cast on that broken arm? -- are no-brainers (at least for those who can afford health care), lots of others are brainers indeed.

The relative benefits and risks of a given procedure or drug can be difficult to evaluate, even for doctors. New information based on medical research can either clarify or muddy the waters. And as one generation of doctors trains the next and parents pass their wisdom on to their adult children (an act otherwise known as "meddling"), the burden of tradition can weigh heavy, even after the tradition has outlived its utility.

A generation ago, when my mom was raising me, kids with chronic upper respiratory problems and lots of sore throats routinely had their tonsils removed. It wasn't -- and isn't -- a risk-free procedure, but moms like mine (who may have been more swayed by medical authority than we are) put a lot of stock in it, especially since it appeared to miraculously halt their child's parade of illnesses. And so she thinks my strep-throat-prone daughter should have a tonsillectomy.

But Mark Weissman, chief of general pediatrics at Children's National Medical Center in the District, says evidence now suggests that what those grateful parents were witnessing was not a miracle but a coincidence. "Kids get a series of respiratory illnesses in the first few years" before their immune systems are fully developed, he says; as they grow, they generally build up resistance and get fewer viral illnesses, whether they have their tonsils removed or not. Today only a small number of children -- less than 1 percent, Weissman figures -- are prime candidates for tonsillectomy, and usually because their tonsils are naturally so large that they threaten to impair breathing (a condition that many outgrow).

Parents in my mom's cohort were also convinced that flat feet needed correction, either through surgery during infancy or charming "corrective" shoes. Today, the consensus is that flat-footedness, dictated by our genes, can't be fixed with funky footwear, has little effect on mobility and should only rarely be addressed surgically.

Even scary-sounding scoliosis, or lateral curvature of the spine, isn't as grim a condition as we grew up thinking it was. A recent study of people who were diagnosed with scoliosis 50 years ago but never put in a brace revealed that they, for the most part, turned out just fine. Weissman says that while all children should be screened for scoliosis during regular checkups, current thinking dictates watchful waiting for mild curvatures and reserving intervention for the small minority of children with severe curvatures.

None of this is to discredit my mom or yours. But it's interesting to see how the sand shifts. And doesn't it make you wonder which of the procedures we hold dear today will be out of vogue in 20 years, just in time for us to suggest they be used on our grandchildren?

The columns KidLife and MidLife, devoted to healthy handling of children and adulthood, appear in alternating weeks. Send comments, suggestions and questions to kidmid@washpost.com. For U.S. Mail, see address on Page F2. No calls, please.