"That's not the Dad I remember," says Geoff, one of Stanley's four younger sons by his second marriage. "Dad had a big heart and he loved us all equally. He was incredibly proud of Elton and everything that he achieved."
As evidence, he tells how Elton was still in his father's thoughts on his deathbed in 1991 with Geoff, Stanley Jnr, Robert and Simon all standing vigil. Geoff says: "A friend said 'You've got four wonderful sons, Stan', to which he replied, 'I've got five wonderful sons.'"
Since then, Geoff has barely been in contact with his brother, preferring to lead an alternative lifestyle in the small town of Ruthin in North Wales, where he hand-makes yurts and harps and organises music festivals. Now however, as Rocketman, starring Taron Egerton, rewrites his own family history, he feels he has to speak out in defence of their father.
He begins by demolishing the image of Stanley as a man incapable of affection, pointing out that his father was as keen on a goodnight kiss from his sons as their mother Edna, Stanley's second wife.
"This coldness, it's a million miles away from what Dad was like," he says. "He was a product of a time when men didn't go around hugging each other and showing their feelings every minute of every day, but he had plenty of love in him for all of us. As a kid, my memories of Dad are of him laughing and larking around. If one of us was upset, he'd do something silly like pretend to be a chimpanzee or he'd start tickling us."
It means Geoff refutes Elton's long-time claim, almost the opening scene in Rocketman, that Stanley, then a Flight Lieutenant in the RAF, came home from a lengthy posting overseas and demanded dinner instead of racing upstairs for a reunion with his son.
"I just cannot believe that," says Geoff. "Dad was the one who registered Elton's birth. He was there when Elton was born and he did not stop caring."
In the film, the young Elton is shown heartbroken, waiting for his father in the half light at the top of the stairs. Elton later shares this painful "memory" with strangers during a group therapy session in rehab for drink and drugs, leaving viewers in no doubt about the emotional scars it left.
Crucially, Geoff also believes the film is wrong about Stanley's lack of support for his eldest son's musical ambitions. In Rocketman, when Elton's mother Sheila, Stanley's first wife, tells him their son is being put forward for a Royal Academy place, Stanley says disdainfully: "Do you really think he has got that kind of talent?"
According to Geoff, Stanley, who adored music, shared his passion with all his sons. "It's rubbish to suggest otherwise," he says."Dad bought a piano for Elton and had it sent round to where he was living with his mother." (This claim is backed by Edna who kept the '68 receipt for the second-hand Collingwood pianoforte with its walnut finish.)
"Dad encouraged all of us to be musical. He was in a swing band himself, so I see no reason why he'd have thwarted Elton. I was hopeless on the piano so Dad left a guitar and a trumpet out for me with a few teach-yourself books. That doesn't sound like a man who discourages his kids."
There is a pivotal scene in Rocketman where the teenage Elton is shown trying to connect with his father through music, rifling through his record collection and holding up an album for them to enjoy together.
But Stanley scolds him and instructs him never to touch the records without permission.
This, says Geoff, does ring true, for Stanley was proprietorial about his records, his toolbox and his favourite green armchair.
"If Dad was out or at work, we'd all fight to sit in it but as soon as he got home he didn't even need to tell us to move, we'd leg it," remembers Geoff. Elton appears to have taken this trait of his father's as a personal insult, nursing his hurt into adulthood and adding it to his catalogue of Stanley's supposed rejections.
There are multiple other points at which Geoff's understanding of the Dwight family's past is at odds with what's depicted in the film.For example, there's the moment the young Elton, clearly wrestling with the possibility that he might be gay, is humiliated when Stanley reprimands him for looking at dresses in his mother's magazine.
"Dad didn't have a homophobic bone in his body," says Geoff. "When Elton came out, he didn't care, didn't even mention it because it wasn't important to him."
Or there's Stanley's supposed response when he discovered Sheila had been cheating on him. In the film Stanley yells he's relieved because it gives him a good reason to divorce her and leave the family, which he did when Elton was 14. "Again, not true," says Geoff. "Dad was devastated when he found out she had been seeing another man. He went round to his house. Fred Farebrother was his name. [Fred later married Sheila.]
"When he knocked on the door, Fred scarpered out the back and he was invited in by the wife. They chatted and I guess shared their sadness and Dad felt so sorry for her and her kids he ended up giving her a tenner before he left. That's what he always told us."
In Rocketman, Stanley is shown walking out, icy calm, in a homburg and trench-coat without even looking back at his son, who is weeping at a bedroom window.
It's true that Geoff and Elton have had hugely disparate lives and that they make unlikely siblings - even though their physical resemblance is clear.
While Elton toured the world making tens of millions of pounds and lavishing vast sums on homes, art, designer clothes and diamonds, Geoff dropped out of the private school to which he'd won an academic scholarship, wound up in jail for his part in a botched burglary and smoked a lot of weed. But he is not envious.
"There's no ill feeling from me towards Elton," he says. "Far from it. I love him but our paths have gone in different directions."
Apart from exchanging the occasional Christmas card, he has not sought a relationship with Elton since he was 16 when he hitched a lift from North Wales to watch him perform in Manchester. "I was wondering if one of you might turn up," said the star dismissively.
Since that tepid reunion, they have only spoken once which was when Geoff told him their father had died. Stanley was just 67 but suffering from complications brought on by heart disease. Geoff tried to broker a final meeting so the pair could make peace.
"I went through the rigmarole of tracking Elton down through his label and management team, leaving messages everywhere, but by the time he got back to me, Dad was dead," Geoff says.
"He'd died the day before. I told him about the arrangements for the funeral and Elton just said, 'No Geoff, I'm not coming.'"
The star later said it would have been hypocritical to go but to Geoff this does not make sense.
"Dad could have been telling me a pack of lies about his relationship with Elton for all those years," he says, "but knowing Dad as I did, I doubt it. He never lied about anything and he and I were close."
This is why he's so hurt seeing his father's memory traduced on film. What gives his account credibility is that it's not just his impressions of Stanley which are at odds with the biopic - it's the events in which he was involved as a child too.
Halfway through the two-hour film, Elton is shown arriving at Stanley and Edna's suburban home on the Wirral in Merseyside where Stanley was by then working for Unilever at Port Sunlight.
Dismounting from his flashy Rolls-Royce, Elton offers his bewildered father a diamante-encrusted Chopard watch as the then six-year-old Geoff looks on.
"I've never seen or heard of this watch," says Geoff today. Moments later, in a toe-curling scene, Stanley asks Elton to autograph an album for a friend at work. "Not Dad's style," says Geoff.
As Elton leaves, Geoff and one of the other brothers rush out to wave goodbye but are shoo-ed back in by their father because they are in their stocking feet. The gulf between the lonely Elton driving away in the back of his Rolls and this warm vignette of family life could not be clearer.
"But that is pure fiction too," says Geoff. "I remember it because it was the only time Elton came to see us. He rocked up in a chauffeur-driven, cream-coloured Rolls-Royce. We were very excited and we did go out into the street to see him off but Dad wouldn't have cared about whether or not we had shoes on. He wasn't like that."
Elton has spoken in the past about what he feels he went through at the hands of his father. Addressing the Oxford Union four years ago, he said: "He never told me he loved me, he didn't hold me, and he didn't come to see me perform. He was taught that love had limits. You don't show it in public. You don't even show it in private. And if your son isn't quite like you, and he's pretty f****** different from you in fact, then your love becomes cut off and inexpressible."
He told how his father did not support his singing career and instead wanted him to be a banker or civil servant: "I've spent the rest of my life trying to prove to my father that I was a success. He's been dead [for] years and I'm still trying to prove the point. It stays with you. And when we had our own children [Elton has two sons Zachary, eight, and Elijah, six, with husband David Furnish] I never stopped telling them I loved them and they never stop telling me they love me."
These bitter claims have already been questioned by his biographer Philip Norman who has seen photos, letters and diaries belonging to Edna showing that Stanley did love and support Elton and that the myth of the abandoned son seems to have been fostered by Sheila in the aftermath of their divorce.
Now they're being tested again by his half brother.
However, given the Oscar buzz surrounding the movie and the fact that Rocketman is currently soaring at the box office, it may be too late to rewrite the lyrics of this particular song.
