An allegation of a child-indecency conviction against the Australian father in the baby surrogacy furore has prompted Gammy's mother to demand his sister be returned to her in Thailand.
Channel Nine has reported that the West Australian man was in 1998 convicted of an indecent act involving a child under 13 and has served a prison term. The report claims his wife knows of the conviction.
As Fairfax Media revealed last week, the couple are accused of taking home an infant girl born to surrogate mother Pattharamon Janbua, but abandoning her twin brother Gammy, who was born with Down syndrome and a hole in the heart.
The biological parents have not been named but the media is focusing on an address in Western Australia.
The ABC's 7:30 on Monday night reported the Australian parents had denied any knowledge of a son as they a negoatiated a "confusing" Thai surrogacy process and language barriers.
Nine also reported that the couple believes Ms Pattharamon is not the surrogate mother they met in Thailand.
Told of the biological father's reported child-indecency conviction, Ms Pattharamon called for his sister to be brought back to her in Thailand.
“I am in shock after hearing this story," she told Fairfax Media from the hospital where a critically unwell Gammy is being treated for a lung infection. "I am very worried about my baby girl.”
“I need help from anyone who can bring my girl back to me as soon as possible . . . this news make me sick.
“I will take care of my twin babies. I will not give her or him to any family that wants a baby.”
Earlier Ms Pattharamon challenged the father to appear with her on television after reports that he had denied abandoning Gammy, claiming a Thai clinic doctor only told him and his wife about the girl.
Ms Pattharamon claims the father came to a Bangkok hospital after she gave birth and saw both the girl and Gammy, but only took the girl back to Australia.
She said she had forgiven the Australian couple but was now considering suing them.
A fundraising campaign has raised almost $220,000 for Gammy's medical costs and long-term care.
Meanwhile, Thai medical authorities have launched an investigation into the Gammy scandal, which the country’s strict military rulers citing it to justify a crackdown on a booming surrogacy and gender selection industry.
Under the crackdown a surrogate can only accept an embryo from a mother who is a relative and it is illegal for money to be given to a surrogate who bears a child, effectively closing down commercial surrogacy in Thailand.
Senior health officials said the investigation would focus on whether those involved in the Gammy surrogacy were properly licensed.
The Bangkok Nation newspaper reported those involved in the Gammy surrogacy faced having their medical license revoked, suspended or put on probation or disciplinary action for lesser offences.