"My hero would have to be my mother. She worked extremely hard to change my life hugely," Emmanuel told X Factor judges before his first performance in September.
Moira, 47, has given her adult life to helping disadvantaged children around the world, including working with Mother Teresa in Calcutta.
"Moira is very determined, very single-minded and, sometimes, challenging too," chuckles Margaret Smith, a good friend of Moira's for over 27 years, who also serves as chief executive of her charity, the Children First Foundation.
"Her Catholic faith has been her driving force to keep going and keep doing all this in New York's Bronx, Calcutta, the Kalahari, Western Australia and all around the world."
The Foundation describes its mission as transforming "the lives of children who need us most by giving hope, exceptional care and pathways to a brighter future." Their "Miracle Smiles" program brings children in need of life-saving or life-changing surgery from the developing world to Australia to receive the care they need.
Because of her desire to help children in such dire straights, Moira went to war-torn Iraq in the mid 1990s. While she was there Moira came across Emmanuel and his brother Ahmed in an orphanage run by Mother Teresa's Missionaries of Charity. The baby boys had been found by the nuns in a shoe box in a Baghdad park. Both were suffering from limb deficiencies because of chemical warfare.
"It was like looking at an angel when mum, Moira Kelly, walked through the orphanage door," Emmanuel told the talent show judges. "She brought us both to Australia for surgery originally and then mum sort of fell in love with both of us."
Soon thereafter, Moira became legal guardian for both boys.
"I think one of the most wonderful things about Moira is that she accepts every child is accepted for who they are," said her friend Margaret. "It takes a gutsy person to devote their life in this way rather than go out and earn a big salary."
With the love and support of Moira, 19-year-old Ahmed has now set his sights on a swimming gold in the 2012 Paralympics in London. Meanwhile, Emmanuel is contemplating a music career, despite his exit this month from X Factor.
"Moira is thrilled to bits. We all are," said Magaret, "it's been a wonderful exercise for him.
"He knows he's going to have to work at it very hard but we've always known he's got a wonderful voice."