The average athlete gives 10,000 hours of "deliberate practice" to develop the expertise to go all the way to the Olympics, according to Gould. "They do it with some yelling and pushing, but in the end, you push yourself."
"Even well-meaning parents can get really caught up in five-ring fever," he said. "You can't use guilt to motivate a kid or love withdrawal."
Gould says it's a "delicate balance." The best parent will ask their children to "follow through on your commitments and the responsibility of good practice."
No parent-child relationship is ever going to be completely "normal" at this level of competition, according to Gould.
Larry Lauer, who is director of coaching education and development at the institute, did a study on the influence of parents on nine professional tennis players.
Athletes with controlling parents thought about quitting at some point in their junior careers. "Those who carried forward decided to play tennis for themselves and not for their parents," he said.
One top-ranked female player told researchers, "My mom would rather have me win a tournament than come home to see her."
When he looked at athletes and their parents over time, the most demanding parents had "strained relationships" with their children.
"When people are constantly under stress it causes them to make other choices to relieve that stress, like drinking and taking drugs or even promiscuity," said Lauer.
As for former Olympic medalist Clarke, she tries to strike a balance with her three children, including 15-year-old Antonio, who is a rising high school basketball and track star.
"I try not to get over-involved," she said. "I used to coach professionally and that kicks in -- and it's a fine line between being a coach and a parent. Intrinsically, they have to see the sport as their core value in their life, otherwise there is resistance when a parent is always pushing them."
"I had to not use my personal drive and how I see sports and impose that on my kids," said Clarke. "They had to figure it out for themselves."