You underestimate the human mind! Gender identity is something that forms around 4-5 years old. So by 10 the child could certainly know that they were transgender.
Response to Have You Ever Stolen Something?:
When I was 5 I stole some bubblegum from the gas station. My dad caught me when we got home and took me back to apologize.
Response to Which Classic Author Is Your Soulmate?: