My granddaughter was born two years ago today, although the celebration of her birth began weeks ago when her parents campaigned her through several southern states to be feted by adoring grandparents and other relatives, and it will continue through this weekend to allow local relatives and friends equal time to cherish her existence.

My granddaughter was born two years ago today, although the celebration of her birth began weeks ago when her parents campaigned her through several southern states to be feted by adoring grandparents and other relatives, and it will continue through this weekend to allow local relatives and friends equal time to cherish her existence.

Family parties in fact began well before the first of the month, when my grandson celebrated his second birthday. Or, I should say, commenced to celebrate, since he, too, claims more well-wishers than one day could possibly accommodate.

This will be the pattern of all Mays going forward, I see now. Of course, no birthday jubilees ever will match the huzzahs of that initial May, when first my grandson and then my granddaughter joined the family in quick succession. Those three weeks are blurry now -- well, they were blurry then, especially for the new parents -- but I retain images of those snugly wrapped bundles being passed from one eager set of arms to another while we all tried not to breathe any germs on such unsullied purity.

My husband went so far as to wear a surgical mask when he visited our grandson on the baby's second day in the world; he had what might have developed into a sore throat and didn't want to risk passing a germ to a creature barely 24 hours old.

Two years later, the babies -- now full-fledged toddlers, with all the rights, honors and privileges appertaining thereto -- have learned to wash their own hands, brush their own teeth and cough into their own elbows, or at least in the general direction of their elbows, all commendable habits.

Meanwhile, their elders' horror of bringing germs within a six-mile radius of the shortest family members has abated considerably. When the babies, brought together by their parents for one of the first of many playdates, decided to swap pacifiers, the occasion was marked not by the parents' rush to stop the germ exchange, but by the delighted clicks of everybody's cellphone cameras.

Other people might cling longer to the ideal of shielding a baby from common household germs, but everyone gives up sooner or later, if only because the baby himself is so clearly the bringer of bugs to the family circle.

Twenty-four hours after our grandson was sent home from day care with a mild fever punctuated by projectile vomiting, neither of which made him particularly unhappy, both my daughter and son-in-law were knocked flat by the same bug.

Between them, it was all they could do to call for help and unlock the back door so the help -- my husband and I -- could come in. They were past caring when I swooped into the marital bedroom to collect the baby -- who by then was positively burbling with good health and spirits -- and carry him away so his parents could be wretched at their leisure.

These painful experiences remind parents and grandparents alike that germs are a part of life. Incorporating them into a baby's everyday routine is how strong immune systems are built. At least, that's how I interpret the evidence.

As an example, I offer my own children, who never went to day care. I worked at home, which is to say I worked when my own children were completely happy and in need of nothing -- not food or drink, not book or toy, not diaper or bathroom, not anger management or assertiveness training, not a life lesson in keeping the beans inside the bean bag or a literary analysis of the puppy's pokiness. In other words, I worked when they were napping, in short spurts that ended abruptly when wails floated down the stairs.

And although a daughter once crawled into the doghouse, scrooching herself into a dark corner, out of sight, until I got down on my hands and knees and stuck my own head through the dog's door; although a daughter once found a beer bottle flung from a car window by a litterbug and -- even as I raced toward her in dreamlike slow motion -- put it to her mouth, both girls remained remarkably healthy until they started kindergarten. At that point, every last germ that ankled down the pike put them to bed with fever and a rash.

Meanwhile, classmates who had worked their way through those germs during their day-care years were impervious to scarlet fever, strep throat and the 17 different strains of common flu that were felling my daughters and, as often as not, me. My older daughter, in fact, didn't come home from kindergarten with the flu; she caught it -- we caught it -- a few days before kindergarten was to begin.

I wasn't concerned at first. For one thing, I was too sick to worry about what might happen a few days hence, and for another, I trusted that we'd both be healthy again in 24 hours.

We weren't, though. This flu had legs, as it turned out -- the kind of legs that pin a person down for a week and a half and leave her feeling spindly and translucent for another fortnight, at least. The first day of school came and went, as did the second and the third. My daughter started kindergarten a full week after her classmates did.

Years later, when she struggled with organizational skills -- "She'd rather read than do our class work," a teacher wrote on a report card -- I blamed those first days of kindergarten when, I assumed, all the other children were taught to write down assignments and then do them.

My point, though, is that all children run through childhood illnesses, and the sooner they get them out of the way, the better the chances they'll be consistently present when school starts playing for keeps.

Now if you'll excuse me, I have birthdays to celebrate.

Write to ThisWeek News columnist and copy editor Margo Bartlett at mbartlett@thisweeknews.com.