Kristina Olson has begun a landmark study to document the experience of transgender children.
http://thinkprogress.org/lgbt/2015/01/30/3617395/transgender-children-study/
http://magazine.good.is/articles/transgender-study
http://kuow.org/post/when-do-kids-know-they-re-transgender-younger-youd-think
http://www.eurekalert.org/pub_releases/2015-01/afps-tks012915.php
http://www.care2.com/causes/think-trans-kids-are-confused-about-their-gender-think-again.html