Image copyright Savejames.com

A Texas judge has given joint custody to two parents locked in a bitter dispute over the gender identity of their child, in a case that has provoked wider debate over the appropriate age for gender transitions.

During the trial, Anne Georgulas said her child - named James at birth - identifies as a girl and wishes to be called Luna.

But the father, Jeffrey Younger, claimed Dr Georgulas has pressured their child to identify as female, and charged his ex-wife with child abuse.

Judge Kim Cooks ruled on Thursday that decisions over issues like medical procedures and psychiatric treatment should be reached by Mr Younger and Dr Georgulas together.

In doing so, she overruled a prior decision by a Dallas jury that voted 11-1 to give Dr Georgulas sole control of the child's medical and physiological care. In Texas parties in custody disputes can opt for a trial by jury, but a judge can review the decision.

The case has sparked outcry on the political right, with conservatives echoing Mr Younger's claims of child abuse.

The Texas attorney general said child protective services would investigate the abuse allegations involving the family from Coppell, a Dallas suburb.

As Judge Cooks issued her ruling, however, she said there was no evidence supporting charges of abuse by either Mr Younger or Dr Georgulas.

Both parents have been barred from speaking publicly about the case. For Mr Younger - who has strongly objected to treating his child as a girl - this means shutting down his website, Save James, which has attracted the support of the political right.

Dr Georgulas, a paediatrician, said her child - who has a twin brother - began to express a desire to be a girl in 2015, when the child was three, asking to wear dresses and look like the female characters from the Disney movie Frozen.

Mr Younger and Dr Georgulas' four-year marriage was annulled in 2016, at which point Dr Georgulas was given exclusive control of decisions regarding medical, psychological and educational issues.

"[The child] has been dressing as a girl in public, going to school in public as a girl, and requests that she be named Luna," a lawyer for Dr Georgulas, Kim Meaders, told a court last year.

At the child's five-year-old medical check-up, the doctor diagnosed the child with "gender identity disorder", Dr Georgulas testified.

After the next annual check-up, the doctor wrote that child was "still referring to self as female".

Image copyright Drew Anthony Smith/Getty Images Image caption Texas Governor Greg Abbott says several state agencies were looking into the case

At trial, Dr Georgulas said psychologists had recommended that she allow the child "to present in whatever way they wish".

"The interviews with teachers, the counsellor's notes and records, Luna herself and Luna's brother all state Luna has always wanted to be a girl... It's not being forced upon her," Ms Meaders said.

Therapists and counsellors who testified confirmed Dr Georgulas' account. Teachers at school call the child Luna.

But Mr Younger argued that his ex-wife had pressured their child to identify as transgender, saying in court that his child had been "perfectly happy as a boy".

He has been outspoken about the harms he believes are caused by a child beginning a gender transition.

"Children who are too young to make the choice can't make the choice," he said in trial.

In a podcast this year, Mr Younger described how upsetting it was for him to see his son during their video chats dressed as "a drag queen" with "false eyelashes and makeup".

He said in an interview with Texas conservative strategist Luke Macias he said that "tampering" with a young boy's gender identity amounted to sexual abuse.

Mr Younger added: "The courts are not going to be fair to you. And the only way you can survive this and get your son through this alive is to calmly allow your son to be tortured right before your eyes and outlast the opposition."

He has said he would allow his child to dress as a girl upon reaching 18 years of age.

The "wait-and-see" approach, advocated by Mr Younger has been described as "outdated" by the American Academy of Pediatrics (AAP).

Treating children's chosen gender identities as "possibly true" can deny "critical support", according to the AAP.

The case has provoked heated response from conservatives, including President Donald Trump's son, Donald Trump Jr, and Texas Senator Ted Cruz.

"This is child abuse," Donald Trump Jr wrote in a tweet.

Announcing the state inquiry, Attorney General Ken Paxton said on Thursday: "Texans understand that children are cherished, unique individuals who should be supported and properly cared for as they grow up in communities."

He said the Department of Family and Protective Services would "conduct a thorough investigation, and protect this child".

During the trial, Dr Georgulas said she would consider hormone suppression once the twin reaches puberty, and only if the child "persists" in identifying as a girl. Dr Georgulas had requested that the court demand written consent from both parents before any treatment involving hormone suppression, puberty blockers and transgender reassignment surgery.

Hormone suppression prevents the development of sex characteristics such as periods, breasts or voice-breaking.

Critics have argued that such treatment would be inappropriate for so young a child.

But health professionals stress that hormone suppressors are never used for a pre-pubescent children. They emphasise that hormone suppressors are only prescribed at a certain stage of puberty ("Tanner Stage 2" - typically between the ages of 10-14) and that the drugs' effects are reversible.

Laura Edwards-Leeper, a clinical psychologist at Pacific University who specialises in gender identity says he finds it astonishing that "people believe that medical providers are offering treatment to young children".

"When there are headlines about sex changes in children, that is completely not true," he told the BBC.

In addition to a physician, many patients will also be seen by a therapist for an assessment, like Dr Edwards-Leeper, before being prescribed puberty blockers.

Media playback is unsupported on your device Media caption Chile's Amaranta school is believed to be the first in the world created for transgender children

Echoing Dr Edwards-Leeper, psychotherapist Wesley Parks said at trial that it "wouldn't be possible" for Ms Georgulas and Mr Younger's child to take hormone blockers at the age of seven.

Puberty blockers are "critical" for children who are struggling with their gender identity, Dr Edwards-Leeper said. It "alleviates the distress that puberty causes for many of these kids before they have to make a decision about possibly irreversible interventions".

Even for the "handful" of her patients who have chosen to go off the hormone blockers, Dr Edwards-Leeper has observed no psychological harm to the temporary delay in puberty.

"It's completely false to say supporting a young child in their affirmed gender is child abuse," Dr Edwards-Leeper said. "It's in the child's best interest."

Recent estimates place the number of transgender adults in the US at 1.4 million - 0.6% of the population age 18 or older.

A transgender person is someone who experiences a gender identity which differs from that of their assigned sex at birth.