Following the verdict, the emotional scenes spilled out of the courtroom, where smiling and tearful family members embraced the teenager.
Speaking outside court, the brother of the deceased said the trial had been "a trying time for everybody", especially his nephew.
"It's been hard for him, but I think this is a huge, huge relief for him. And obviously all the emotions, it's great from the family point of view," he said.
"We can move on together. It's great because [my nephew's] life has been put on pause in more ways than one. Now we can have a plan I suppose, move forward together as a family."
The trauma of the trial had been compounded by the death of the teenager's grandfather, just two months after his father's death.
The uncle said charges should never have been laid, and the family would have gone through huge stress and trauma had the verdict gone the other way.
"It is a tragedy for all parts, and nobody's a winner ... The winner at the end of the day is justice has prevailed."
The uncle said he had no doubts about supporting his nephew through the trial.
"He lives with me, he looks after my children ... I trust him fully with all of them."
Speaking outside court, defence lawyer Bruce Squire QC said the fact the jury reached a verdict quickly was a clear indication that his client should never have been charged.
"I think it was a mistake on the part of the prosecuting authorities to charge him with the serious offence of manslaughter based on the very tenuous case that the Crown presented at the trial."
Mr Squire said the trial had been a considerable burden and had "a terrible impact" on his client.
"He was very upset and distraught during the trial. He managed to keep himself composed very well for a young man."
During the trial, the jury heard the then 18-year-old got into a verbal argument with his sister, after which their father was called back home to sort the issue out.
The son became angry and frustrated that he was not being listened to, and pushed his father onto a bed and hit him in the gut several times.
The argument continued outside, where the son again shoved and hit his father several more times.
His father became winded before he collapsed and died of heart failure.
Crown prosecutor Ian Murray told the jury that the stress of the altercation was "undoubtedly the substantial cause of the heart attack".
Mr Murray referred to evidence from a pathologist who said the cumulative stress of the physical and verbal altercation had the capacity to cause the father's heart to fail.
"This is a tragedy and undoubtedly the accused did not mean to cause his father's death."
Mr Squire told the jury his client had not hit his father with force, and neither man had suffered physical damage from the blows.
He referred to evidence from a cardiologist that the father's heart condition was such that any out-of-the ordinary stress could have caused his death.
Mr Squire said the stress of dealing with the siblings' argument and a subsequent verbal argument with his ex-wife could have contributed to his death.
The ex-wife had blocked in the deceased's car, meaning he was unable to leave as planned.
Speaking outside court, the man's sister said she had no doubt what killed her brother.
"If his ex-wife had not blocked him in the driveway, he would have driven away."
She said she was glad her nephew had been cleared.
