In response, Mr Younger asked the court to grant him sole custody, arguing his son was not transgender. The jury verdict on Monday rejected his request, ruling the children should stay with Dr Georgulas and paving the way for James' transition.
A judge is expected to issue a formal verdict on Thursday in the drawn-out custody battle, The Texan reports, which has sparked outrage among conservative and religious circles in the US and spawned the viral hashtag "SaveJamesYounger".
The Governor of Texas weighed into the controversy late on Wednesday. "FYI the matter of seven-year-old James Younger is being looked into by the Texas Attorney General's Office and the Texas Department of Family and Protective Services," Greg Abbott tweeted.
Transgender advocates had welcomed the decision and accused the right of whipping up a transphobic "panic" over the case, arguing it was actually Mr Younger who was doing damage to James by forcing him to dress in boy's clothes against his wishes.
According to The Texan, expert witnesses called by Dr Georgulas were mostly therapists and counsellors who said James told them he was a girl, while Mr Younger's witnesses had not met James but were medical professionals who pointed out the dangers of "social transition" and the "medical transition" it usually leads to.
Dr Benjamin Albritton, in sworn testimony last week, expressed doubt that James was fully convinced he was female. "There is still some fluidity in his thinking," he said. "Neither child appears to be depressed, anxious or aggressive … (James) gave no indications of other significant psychological difficulties."
Dr Albritton compiled a report for the court advocating an "affirmation" approach but recommending the court prohibit Dr Georgulas from initiating a medical transition without approval from Mr Younger, The Texan reports.
The judge could include Dr Albritton's recommendation in her verdict on Thursday. Mr Younger could appeal the jury's decision, but is concerned that James could already be on puberty blockers by the end of that process which could take up to a year.
Dr Georgulas provided a letter from a gay children's therapy centre recommending James become a patient of Dallas transgender children's clinic Genecis "so that she can receive a full psychological assessment for gender dysphoria and potentially take hormone blockers".
Court transcripts from the hearing in July last year show Dr Georgulas, under questioning from her lawyer Kim Meaders, reading from James' medical notes from when he was five years old.
"'Dressing in girls' clothing. Mom has met with psyche via Genecis Clinic at UT Southwestern CMC'," Dr Georgulas said, quoting the pediatrician's notes. "'Luna also meeting with psychological monthly. Will plan to have eval at Genecis when closer to eight to nine years old to consider hormone suppression.'"
Ms Meaders said, "Okay. So was that something you planned to do when the child gets closer to eight or nine or is that something she suggested?"
Dr Georgulas said, "Well, that's the recommendation, that's what Genecis suggests, that's what she's talking about, but that would only be if she persists."
Ms Meaders said, "Okay. So you're not doing hormone therapy now?" — "No." — "And you're not trying to do any chemical castration as Jeff accuses you of?" — "No."
Mr Younger launched a website last year called SaveJames.com, where he urges people to donate towards his legal expenses to fight the "chemical castration and sex-change of his seven-year-old son".
Critics have called his credibility into question. The couple married in 2010 and sought an annulment in 2016, with a court ordering Mr Younger pay his ex-wife damages of $US45,000 for theft and ruling he had committed fraud by "inducing" her into marriage by lying about his employment history, income and military service.
Texas Republican Representative Chip Roy was the first politician to directly weigh in on the case, writing on Twitter, "This lunacy in our society is fundamentally altering this young boy's life."
He also was quoted telling The Blaze, "We are fundamentally damaging young boys and girls because we are allowing our culture to make them an experiment in some fad and we should be ashamed."
Texas Republican Senator Ted Cruz tweeted on Wednesday, "This is horrifying and tragic. For a parent to subject such a young child to life-altering hormone blockers to medically transition their sex is nothing less than child abuse."
He added, "A seven-year-old child doesn't have the maturity to make profound decisions like this. The state of Texas should protect this child's right to choose — as an informed, mature person — and not be used as a pawn in a left-wing political agenda."
