Thomas Lobel, who now calls himself Tammy, is undergoing controversial hormone blocking treatment in Berkeley, California to stop him going through puberty as a boy.
But Pauline Moreno and Debra Lobel warn that children with gender identity disorder forced to postpone transitioning could face a higher risk of suicide.
The mothers say that one of the first things Thomas told them when he learned sign language aged three - because of a speech impediment - was, 'I am a girl'.
At age seven, after threatening genital mutilation on himself, psychiatrists diagnosed Thomas with gender identity disorder. By the age of eight, he began transitioning.
This summer, he started taking hormone-blocking drugs, which will stop him from experiencing puberty.
The hormone-suppressant, implanted in his upper left arm, will postpone the 11-year-old developing broad shoulders, deep voice and facial hair.
The couple faced intense criticism from friends and family as a result, Ms Moreno told MailOnline.
'Everybody was angry with us. "How could you be doing this? You might be ruining his whole life!"
Citing a statistic from the Youth Suicide Prevention Program, Ms Moreno noted over 50 per cent of transgender youth will have had at least one suicide attempt by their 20th birthday.
And ignoring their son's incessant pleas, she said, simply was not worth the risk.
'What is so frightening to me is that you would be willing to say "no" just because you don't like it - even though your child could lose their life?'
Her son's adolescent transition, she hopes, will help him have a less conflicted adulthood.
'The whole idea now is let's stop creating a third (gender) that is neither one thing or the other, so we transitioned her,' said Ms Moreno.
'The protocol now is to transition these children as soon as you can make a diagnosis, because otherwise they end up being not one thing or the other... because they experienced puberty.'
I have nothing more to say.