WHERE DO these kids come from? Chances are you'll be asking that question if you watch the Winter Olympics that open next Saturday. For 16 days and nights thereafter, television screens around the world will be filled with images of men and women coaxing impressively-honed muscles to perform at the edge of human possibility. Most of these men and women will be young. More than a few will still be in their teens.

Athletic genius -- that mysterious blend of grace and power and uncanny reflex possessed by a Larry Bird or a Willie Mays, a Pirmin Zurbriggen or a Katarina Witt -- is always electrifying to behold. To see that kind of genius wrapped in the body of a child is enough to make one's head spin.

It seems as if more and more of the loftiest slots in sports are being usurped by teen-agers: A 15-year-old gymnast becomes the first person to be awarded a perfect score of 10.00 in the Olympic Games; national swimming records are captured by youngsters still in junior high school; pink-cheeked tennis players with braces on their teeth knock off Wimbledon champions. What magic transforms some children into world-caliber performers at an age when the majority of their contemporaries are struggling to master the rudiments of the stick shift? If you guess that parents -- through their genes and their rearing -- are a crucial factor, you're right. But probably not quite in the ways that you imagine.

Inheriting a set of world-caliber genes, certainly, has a lot to do with it. But, just as certainly, much more than hatching a kid with kick-ass chromosomes goes into the making of a Robby Naish -- the Hawaiian boardsailor who won his first windsurfer world championship in 1976 as a skinny, 87-pound 13-year-old and has recaptured the sport's premier title every year since -- or a Boris Becker -- who won his first Wimbledon title in 1985 at the age of 17.

The old question of nature versus nurture comes up right away in any analysis of athletic prodigies, and the evidence is compelling that subtle aspects of family interaction have at least as much bearing on the creation of a prodigy as his or her lineage. Virtually every coach and sports psychologist I spoke to while researching this article emphasized that, without question, the shaping of the psyche factors as heavily into the championship equation as the engineering of the physique.

In "Little Winners," teen-skating-star-turned-author Emily Greenspan points out that many physically gifted young athletes who shine early also burn out early from psychological rather than physical pressures. "For in sports, as in other aspects of life, those who survive tend not only to be the fittest but also those with stronger personalities. Psychological studies indicate that successful athletes in all sports consistently show fewer signs of psychopathology and lower levels of anxiety, neuroticism and depression than less successful athletes and the general population." Greenspan goes on to note that competitors may have widely different types of personality, but they all seem to share one trait: emotional stability. "Those without strong self-assurance," she writes, "simply aren't strong enough to perform well consistently." Sports psychologists Bruce Ogilvie and Thomas Tutko agree that along with the laurels bestowed upon young champions comes tremendous stress. In a Psychology Today article entitled, "Sport: If You Want to Build Character, Try Something Else," they elaborate: "A very young athlete often must face in hours or days the kind of pressure that occurs in the life of an achievement-oriented man over several years. The potential for laying bare the personality structure of the individual is considerable. When the athlete's ego is deeply invested in sports achievement, very few of the neurotic mechanisms provide adequate or sustaining cover. Basically, each must face his moment of truth and live with the consequences."

The pressures magnify almost geometrically as you go up the sports ladder.

When the child is young," Ogilvie explains, "sports are a very innocent thing. The demands are there, but they aren't that important. The child starts doing something because he or she has some aptitude and finds joy in it. But then the parents start getting their needs involved, and then the neighborhood, school, community, state, nation and world enter in. When children reach the age of about 16 they begin to feel social responsibility. Their performance has to be of a certain order or they feel they have disappointed their parents, coach, fans or the press."

Those teenage jocks who do manage to grapple their way to the top of the heap -- however disparate their personalities may otherwise be -- invariably prove to have remarkably tough, resilient psyches. One way or another, the burr of powerful ambition -- an insatiable hunger to excel -- must become firmly lodged under the saddle of a prodigy at a very early age. The complex, murky dynamics of almost any family will generate a wealth of opportunities for such a burr to form. Ordinary sibling rivalry, for example, or routine oedipal tension, or the fallout from a bitter divorce could easily do the trick. What puts the right burr in the right place to bring about brilliant achievement rather than adolescent rebellion or self-destructive behavior is, however, far from understood.

Most surprising, perhaps, is the picture of the appropriate parental model for real-life super kids. Forget the stereotype of the meddling and overbearing Little League dad, or the pushy mother of the classic tennis brat. According to Greenspan, a key quality in parents of prodigies who not only start competing very young but are still going strong 10 years down the road is the ability "to convey enthusiasm without conveying expectation. They reward their children more for trying than for winning."

Take, for example, the parents of the aforementioned Robby Naish. (Though Naish's name is hardly a household world in this country, throughout Europe and Japan -- where a single sailboard race on the World Cup circuit might draw 100,000 spectators -- he is beseiged by autograph hounds and would-be groupies wherever he goes.) Steve Wilkings, a sports photographer who has been a longtime friend of the family, told me that Naish's parents are "for all intents and purposes adventurous, athletic, ex-Berkeley flower children."

This is an important point. The elder Naishes are both high achievers, but they're not the controlling, aggressive parents that one associates with high-performing children. Wilkings explains that "Rick, the father, instilled in the kids -- by example more than anything else -- an intense desire to excel at whatever they chose to do, but there was never the least bit of push; his attitude was like, 'Hey, whatever you want to do is cool with me.'"

A generous dose of non-judgmental, no-strings-attached encouragement, however, is by no means all that budding superstars demand of their parents. Greenspan points out that as the young athlete "starts to achieve, the parental role expands. Mothers are called upon to chauffeur the child to daily practice sessions, competitions, exhibitions. Fathers must annually produce thousands of dollars for equipment, coaching, travel. Siblings, too, must make sacrifices. Often their share of their mother's attention dwindles. And they see that a sizeable proportion of the family budget is allotted to their sister or brother, not to them.

"A child's sports career," Greenspan continues, "is like a flooding stream, sweeping the entire family into the current. By necessity, the family must draw together to coordinate schedules and juggle finances. Psychic boundaries between family members blur as joys and sorrows are communally shared. Yet keeping the family together, identities separate, and the athlete's career going requires a flexibility and continuing commitment that only a few families can successfully muster."

So the parents of young athletes who achieve great and enduring success make a point of being there when their progeny need a pat on the back or money to attend training camp. But they pointedly refrain from burdening the kids with the freight of their own unrealized ambitions, never carp at them to train harder, wouldn't dream of criticizing a subpar performance. Be warned, however, that if you're thinking of forging little Johnny or Suzy into a world-beater, there is no sure-fire recipe for success no matter how impressive their gene pedigree or how well-tempered and steadfast your parental ambition. David Feldman, a psychologist from Tufts University who has studied child prodigies at some length, has pointed out that for genius of any kind to occur, "all of the things that go into it must coincide at exactly the right time, in exactly the right place, under exactly the right conditions." The occurrence of genius -- athletic or otherwise -- remains, more than anything else, a cosmic accident.

Atall, lithe 18-year-old from Juneau, Alaska, named Hilary Lindh, is one such cosmic accident. Most notable among the things Lindh does so much better than the rest of us is going fast on skis. On Feb. 18 she will represent the United States in the Olympic downhill at Calgary.

Nothing in the resume of either Lindh parent (she is currently employed by an airline; he is a land-use consultant to the State of Alaska) broadcasts the existence of world-class genes in the blood line. Both parents are enthusiastic skiers, though, and started taking their daughter up to the local slopes when she was still a toddler. Lindh remembers "days when I'd cry because instead of getting to watch Saturday-morning cartoons, I'd have to go skiing."

Somewhere along the line, though, Lindh became enamored of the cold, fast sport: By the age of six she was racing -- and winning -- regularly, most often against boys; by the time she was 14 she'd won a national Junior Olympic downhill title. "It was about that time," she says, "that I decided to get serious." With her parents' backing, she left home as a ninth-grader to attend a prep school in Salt Lake City with a distinguished ski racing program.

In 1986, at the age of 16, she became the youngest member of the U.S. alpine ski team, outraced the best skiers in North America to win the U.S. national downhill, and took the junior world downhill championship. Despite capturing second in last year's national downhill at Crested Butte, Colo., Lindh was disappointed by her first full season in the World Cup big leagues. She explains that "it was really hard for me not being at the top; it's hard to get used to not being right up there all the time."

Moreover, near the end of the season -- after winning all the training runs at the 1987 junior world downhill championship in Norway -- Lindh caught a ski in some loose snow and suffered a wicked, 60-mph eggbeater crash that ripped out most of the cartilage in one knee. When she got out of the operating room she was on crutches for three months, and had to sleep hooked up to a bizarre, robot-like contraption that continually moved her leg up and down to grind the joint smooth as it healed.

Incredibly, for all these travails, Lindh seems to have recovered her full physical prowess (already in the 1988 season she has placed 10th in a difficult World Cup downhill), and Olle Larsson -- the respected Swedish ski coach who founded Rowmark Academy -- believes that the horrible crash left her confidence and courage -- traits absolutely vital to a downhiller -- completely unbruised. Because of her youth (most downhillers don't peak until their mid-20s), nobody is picking Lindh to take the gold medal at Calgary, but there are those who predict she will achieve great things a little further down the road.

"The injury won't affect Hilary's mental state at all," says Larsson. "She has a very strong personality; it is her mental strength, even more than her physical skills, that make her an outstanding skier. Her personality, in fact, is remarkably similar to a number of skiers I have met who dominated the sport at one time or another: people like Phil Mahre, Ingemar Stenmark, Marc Girardelli and Gustavo Thoeni. All these skiers, Hilary included, possess tremendous self-confidence. They are slightly introverted, have little need to talk about themselves and have a well-developed ability to focus -- to discriminate between what is important and what is trivial. They are also able to focus unswervingly on goals, even when those goals are very distant." People like Lindh, Larsson maintains, can be relied on to rise to the occasion when the chips are down: "They might not in fact be the best athletes in training sessions, but when everything is on the line -- when they are standing in the starting gate at a world championship or the Olympics -- they can be counted on to do their best. Hilary is like that because she competes to please only herself, not to please others, and therefore doesn't feel pressured."

Larsson believes that the actions of parents, above anything else, are responsible for creating an athletic prodigy. "Something that stands out when you look at the parents of successful children like Hilary," he says, "is that they are role models in terms of being very hard workers. Additionally, her parents have supported her in every way possible, but without being pushy.

"I once asked Carlo Fassi {the renowned Italian figure-skating mentor who coached Peggy Fleming, John Curry and Dorothy Hamill} what similarities he sees in the parents of champions," Larsson goes on, "and he told me they vary in every imaginable way, except for one common trait. And that is that they never criticize a kid's training habits or performance. They are there for the kids, and they might occasionally make suggestions, but they do not criticize. It is parents like that who produce great young athletes like Hilary."

Jon Krakauer, a free-lance writer living in Seattle, is a frequent contributor to Outside magazine, where he published an earlier look at superkids.