Most, but not all transgender children are fully aware that they are not like others of their own gender by the time they are old enough to talk. Often, their parents can see the indicators by the time the child learns to walk.
What complicates things is when adults try to repress a transgender child. Sometimes the parents don't even realize the child is being repressed. For example, a father may make homophobic statements or call the boy a "sissy faggot" when mom's not around.
By first or second grade, transgender kids are already struggling with their forced gender. Transgender girls forced to live as boys are often severely bullied, suffering frequent violent attacks. Transgender boys forced to live as girls also find themselves frustrated, often getting into fights with other girls and even other boys.
Many non-transitioning children begin to isolate. Sometimes this is mistaken for some form of autism such as autism. They may become avid readers, spend hours at the computer, or bury themselves in music. Ways to avoid people and still put their excess time to some productive use.
Spotting the transgender girls is pretty easy, look for multiple visits to the nurse's office, especially after gym, lunch, or recess. Watch for who leaves the school an hour or more after the other kids have left (staying after class means less risk of being attacked on the way home).
Doctors often see patients with bruises on arms or face, but bruises on the torso and thighs a a good indication of an attack by a large group of boys, going after targets where the bruises won't show.
Unfortunately, all this violence, almost ALWAYS unreported, tends to make it even harder for a transgender girl to admit that they are transgender. They may deny it because they are afraid of being a target for more violence. They may say to someone they trust "I WANT to be a girl" rather than I AM a girl, because they have been told they are not a girl so many times that they no longer know how to describe the struggle between their girl brain and their (barely) boy body.
A child who has been battered and abused daily, with no intervention by teachers will find it nearly impossible to to ANYONE, because they are so traumatized.
All this only makes the dysphoria worse. The isolation becomes more consistent and persistent. During puberty, they are often moody, even suicidal. Too many are misdiagnosed with clinical depression when the real problem is situational depression. Their bodies are changing in ways they don't want. Transgender girls see hair growing and they see themselves as monsters, like werewolves. Transgender boys see their breasts developing and see themselves becoming street whores.
Those who actually kill themselves are only 1/3 of the gender dysphoria population. Others turn to alcohol, drugs, sex, and overeating, suicide on the installment plan, often in a self-destructive spiral.
Ironically, at any stage, there is a simple treatment that is about 90% effective. Transition. Transition is a process that takes two to four years to complete. Step one is living full time at home, usually evenings and weekends at first, then through the summer, if the desire to transition persists, then going to school full time as a girl is recommended. Many children change schools for this process, or they have made friends with other girls their age who will help and support them.
Keep in mind, if a transgender girl decides she wants to go back to being a boy, that's it! Contrary to myths perpetuated by Conservative Christian Right Wing groups, the school programs to support transgender kids to not permit "commuting".
They don't get to be a girl for a week, then a boy for a week, and back and forth anytime they choose. Their behavior has to be persistent and consistent. They have to look, act, dress, sit, walk, and talk like a girl all day every day for the entire school year.
If someone is just a cross-dresser, the clothes will lose their power to thrill, and they will decide for themselves not to transition, at least not at that time. Many transgender girls get very confused about clothes vs social and behavioral patterns. It's only when they can accept themselves fully as girls that they are ready to transition. In the meantime, the clothes give them an outlet that can ease some of the pain and suffering of their dysphoria.
I know that no cis-gender person can possibly imagine what it is like to be transgender. I wouldn't wish that on my worst enemy (if I had any enemies), but I also know that I will never know what it is like to be cis-gender.
We know that there are real biological and physiological causes for gender ambiguity and gender dysphoria. Gender ambiguity is more common than cleft palate. When you combine all forms of gender ambiguity, the odds of having a dysphoric child are greater than 1 in 100.
Remember, most statistics only identify the most severe forms of dysphoria, those who seek HRT and GCS, which is currently estimate at 3 million in the United States. We know that this is only about 5-10% of the entire transgender population. Gender dysphoria in more mild forms may occur in as many as one in 15 children.
They may be hiding their dysphoria from an unsupporting parent, trying to avoid persecution by the peers they are forced to play with, or just have fears that once they do share their secret, they will be denied help, or denied help, love, and caring.
This is what makes Gender Dysphoria different from being transgender. There are millions of children with Gender Dysphoria who masquerade as cisgender children until they kill themselves. It's only when the police investigate the suicide that they discover the child's true nature, and the bullying related to it.
If your child had a deadly disease that killed 80% of it's victims, but could be treated with simple medications and a relatively inexpensive surgery when they reach the appropriate age, would you tell the doctor not to give your child the medication? Would you tell him not to do the surgery?
Acute Gender Dysphoria is a deadly disease that kills 80% of those who suffer from it. Those with the condition are not able to accept their birth designated gender and are not able to transition to their preferred gender. This may be due to parental non-support, peer pressure and persecution, or religious persecution.
Being transgender isn't the problem. Transgender kids who transition are generally quite happy and healthy and have suicide rates slightly lower than the general population.
If anything, the problem is not that kids are transitioning too soon, but rather they are forced to wait for the life-saving surgery. To have a normal sexual and social life, they need surgery when they are 16, but are forced to wait until they are at least 18 years old.