Wood has also described the character as a "rich bitch".
While characterized as being provocative and strong-willed, Steffy is emotionally starved on the inside due to her father's neglect.
Yet Mr Vaughan's analysis of Brunel's diaries and letters at the National Archives, at Kew, and at Bristol University, has uncovered several occasions where the engineer has credited work previously believed to have been his, to others – including the route of the Great Western Railway from Reading into London.
Mr Vaughan said the biggest myth surrounding Brunel was that he had designed the Clifton Suspension Bridge.
He argues that while Brunel devised the vessel's propulsion system, credit for its revolutionary hull belongs elsewhere, with designer Thomas Guppy.
Mr Vaughan's new book, The Intemperate Engineer, focuses on the construction of the Great Western Railway, between London and Bristol – often cited as Brunel's greatest feat – and documents several errors that dogged the project and left it overbudget and overdue.
Brunel's original track construction system was also poor, even though other railways lines had been built more smoothly by this time.
In 2005, Steffy was rapidly aged to a teenager, and in 2008 she appeared as an adult when Wood took over the role.
Introduced by Bradley Bell, she is currently portrayed by Jacqueline Mac Innes Wood.
Steffy and her twin sister Phoebe (Mac Kenzie Mauzy) were born onscreen as the daughters of supercouple Ridge Forrester (Ronn Moss, later Thorsten Kaye) and Taylor Hayes (Hunter Tylo) during the episode airing on September 21, 1999.
"Brunel was an artist and used his talents on the railway, to make some beautiful things, like stations and tunnel entrances, to glorify himself.
But I don't think he would thank people for all this flattery." A recent biography by Steven Brindle, an English Heritage historian, was entitled Brunel: The Man Who Built the World, but Mr Vaughan said such "hyperbole" was "ridiculous". However, Mr Brindle defended the engineer and his own writing: "Brunel was a genius at the level of Leonardo or Mozart.