Children are whole persons. Children are not partial persons who will be whole once they grow up, or once they develop the capacity to reason. Jesus himself was a child; a whole person at each stage of his development and this is true for every child.
Has Urs von Balthasar puts it like this,
“[it] is a profound mystery, rooted in the very being of Christ, whose identity is inseparable from his being a child in the bosom of the Father.”
The Incarnation is proof enough that children are whole persons. Like all children Jesus experienced the state of childhood. Childhood did not lessen his Incarnation, or render him less than human.
Irenaeus seemed to think so too, in Against Heresies, he says,
“For he came to save all through means of Himself—all, I say who through Him are born again to God—infants, and children, and boys, and youths, and old men. He therefore passed through every age, becoming an infant for infants, thus sanctifying infants; a child for children, thus sanctifying those who are of this age.”
Honoring the whole person of the child looks like acceptance of the child and his or her experiences without comparison or judgment. It looks like accepting who they are at the present moment. Just as Jesus was still Jesus in complete fullness at ten years old so the child present before us is also wholly who they are meant to be at their present age.
 Hans Urs von Balthasar, Unless You Become Like this Child (San Francisco, CA: Ignatius Press,1988), 11.
 Irenaeus, Against Heresies Book II: Chapter 22, 4, accessed February 22, 2016, http://www.newadvent.org/fathers/0103222.htm.