John McEnroe Jr. said "unkind word[s]" about John Sr. in his Tennis Hall of Fame acceptance speech. Johnny Jr.--a national if not worldwide treasure, claimed that his combative court manner was learned at the dinner table directly from John Sr. He said he'd been raised to think people should behave that way.
Contrast that with the lesson Bjorn Borg learned when his parents pulled him off the Junior's circuit for a year because he threw a tantrum. I do not think anger management had anything to do with either man's success.
Nor did "crazy parents" contribute to either man's success: nor for Sampras, Conners, Courier or the Williams sisters.
There is the issue of the Nick Bollettieri Tennis Academy in Bradenton, Florida where some student had absolutely Dickensian experiences: where childhoods are sometimes traded for early exploitation of talent.
I happened to live in Tampa, Florida a couple decades ago. I was playing on the University of South Florida varsity courts when the university's team showed up. They did not need all the courts and so when the coach told us we had to leave to let a young girl play, I challenged him as to why we--as fully grown taxpaying interlopers, should leave for a child. He told me it was because she was the number 11 woman player in the world. We did what was appropriate and quit playing and started watching.
The child turned out to be Mary Pierce. Her father wasn't with her that day--perhaps held off the by univerity's coach, but we got to see him in action not long afterwards. He came to other USF courts with Mary and her little brother one night and conducted a "coaching session" that included yelling, cursing, threatening, hitting balls at the younger brother and various other abusive behavior directed at his children.
As we were an adult foursome--with two large males present, We discussed whether or not we should save the children much grief by walking the court being used by the Pierce family and kicking the living shit out of that evil child-abusing madman. Being lawful persons we, in the end, did not, but always felt bad that we did not.
I'm sure Mary Pierce agrees with me that all the success she's had is of secondary importance to the peace she seems to have found coming out of the turbulence of that abusive parenting. No child should be treated that way for any reason. Not for a second.