The teenage son of a disabled artist who posed while pregnant with him for a Trafalgar Square plinth sculpture has died as his family urges others “not to hold things in”.Parys Lapper was just 19 when he was found dead on August 13 at a house in Worthing, Sussex.He was the son of Alison Lapper, who has shortened legs and no arms. Nearly 20 years ago, she was the model for the marble artwork which appeared on the Fourth Plinth in London and at the opening ceremony of the 2012 Olympics.In a statement on Facebook, Si Clift, Ms Lapper’s fiance, said the teenager “died suddenly”, before urging others to seek help if experiencing difficulties. Sussex Police is investigating the cause of his death.Mr Clift wrote: “Why does it take a passing of life cut short to prompt our hearts to be moved in such a way?“Please take away from this a realisation that you are not alone, that you can talk and not to hold things within. Whatever it is, there is help.” Ms Lapper was born with phocomelia, a condition that causes defects similar to Thalidomide. In 2000, his mother posed naked while eight months pregnant for the artist Marc Quinn.Ms Lapper had been initially reluctant to be the model for the artwork because she was concerned about how her disability would be portrayed. However, Quinn told her that numerous sculptures existed where limbs were missing. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. Marc Quinn’s sculpture ‘Alison Lapper Pregnant’ in Trafalgar SquareCredit: Ian Jones His sculpture, called Alison Lapper Pregnant, was displayed in Trafalgar Square from 2005 to 2007, and a replica featured at the opening of the Olympics when held in London. In 2003, Ms Lapper, who obtained a first-class honours degree in fine art, was awarded an MBE for her services to art.In his statement, Mr Clift described Parys as a “mischievous, generous, kind, loving, frustrating, cheeky, forgiving, beautiful boy.”He has urged local motorcyclists to join a procession following Parys’s coffin to Worthing Crematorium because the teenager was a motorbike fan. “Ali has expressed a dear wish that she would absolutely love to see as many noisy motorbikes as possible to escort Parys on his final journey from her home to celebrate his life.”He added: “Ali Lapper and I are blown away by your kind responses and so appreciative of your kindness … Keep Parys in the forefront of your minds and hearts for a long while.”A spokeswoman for Sussex Police said there were no suspicious circumstances surrounding Parys’s death, adding that results from a post mortem examination are still awaited. Alison Lapper alongside the sculpture in Trafalgar SquareCredit: Ian Jones Ms Lapper, a respected artist from Brighton, had described Parys as “my greatest piece of artwork and creation” after facing considerable opposition to bringing him up on her own.She has never named Parys’s father, who was understood to have left before he was born. After his birth in 2000, she said: “When I saw him, I just cried and cried. The emotions I felt were indescribable. I had never imagined I was going to be a mother, never thought it could be possible. “But when they placed him on my shoulder and I gave him a little kiss on his head and said hello, I was overwhelmed.”In 2010, Parys appeared in the BBC series Child of Our Time, presented by Professor Robert Winston, which charts the lives of 25 children as they reach their 20th birthday. He added that Ms Lapper, 54, had been “blown away” by people’s kindness since the death of her son, whom he described as “his own man” and a “good son”.