id also be remiss if i didnt cite early childhood development studies & more than several research papers out of Sweden on transgender individuals.

youd have to do an extensive reading on early childhood development & make correlations to transgender children , in play activities, childhood development phases. there are some studies that are public by researchers on gender & childhood development but not many corrolate to gender identity except by ancedotal reference, such as speech development. typically by age 3 toddlers learn language to communicate & in communicating, children identify themselves as such & such. so gender issues that become apparent to a parent, is a child's verbal communication to the parent. children do know who they are &say so & will argue with adults or parents about it.