The mother of transgender double rapist Isla Bryson has declared: 'I believe you have to be born female to be female.'

Bryson, 32, was jailed for eight years in February 2023 after raping two women in West Dunbartonshire and Glasgow.

The sex attacker was charged with the offences as Adam Graham, but changed gender while waiting to stand trial and took the name Isla Bryson.

The case sparked public outcry, including from Harry Potter author JK Rowling, after Bryson was sent to the all-female Cornton Vale prison outside Stirling, before later being transferred to a male prison.

Janet Bryson, who refers to her child as 'my son', has now waded in on the row, telling the Sunday Mail: 'I believe you have to be born female to be female. No wigs, dresses or amount of make-up makes you female. 

'You can say you're a woman, but to be female, that is down to biology and how you are born.'

Mrs Bryson made the astonishing comments as she tries to help Scottish feminist campaigners who are trying to win a landmark legal case at the Supreme Court.

The For Women Scotland group last week urged the Supreme Court to confirm sex was 'immutable' and could not be changed by gender recognition certificates.

Bryson's case came amid a controversial row over former Scotland First Minister Nicola Sturgeon's plan for a gender self-ID law, which would have allowed anyone aged 16 or over to obtain a GRC by signing a declaration.

The outcry over Bryson being sent to a female jail contributed to the end of her tenure as First Minister.

Mrs Bryson also rejected the claim that Bryson wanted to become a female from the age of four.

She told the Sunday Mail: 'My son never expressed any wish that he wanted to be a girl, dressed in any other way or ever asked to be called by any other name than Adam growing up,' she said. 'Never once, at the age of four or at any other age.'

Mrs Bryson has previously said that her child's eight-year sentence was not enough and that he should have been locked up for at least 20 years. 

Last week, lawyers for the Scottish Government told the Supreme Court that a person with a GRC is 'recognised in law' as having changed sex. 

Ruth Crawford KC told the Supreme Court that a person would ‘become the sex of their acquired gender’, when they had a GRC.

She was asked by the judges how that squared with physical issues affecting people born women, such as pregnancy or cervical screenings.

She said the ‘pregnant man’ issue was ‘very clearly a matter of deep political water’ that should be left for parliament to resolve or treated as a ‘matter of fact’ regardless of a GRC. 

In a written submission to the court, the Scottish Government said protections for pregnant women in the 2010 Equality Act could also apply to a ‘pregnant man’ who was born female. 

But speaking to the media in Edinburgh during the hearing, First Minister John Swinney was asked if he personally believed it was ‘possible for men to become pregnant’ and replied: ‘No, I don’t.’

Asked why his lawyers were arguing at huge public cost that it was possible, he said ‘many complex arguments’ were being advanced in court.