Age, in itself, is a controversial topic.  Whether it matters, what about it matters, if we should respect it or treat every age equally, etc.
One big thing I’ve noticed is those who refuse to believe that anyone under a certain stage in their aging is capable of understanding their own identity.  As if brain development has anything to do with the primal instinct that is gender.  Even after story upon story of small children committing suicide and mutilating genitalia and the shared depression within the trans* youth community, there are some who still refuse to believe that we know anything about who we are because we are not old enough to buy cigarettes.

A child understands who they are completely and fully.  There is a point when society starts pressuring them into boxes, but the first few years of their lives is in total bliss.  They are completely at ease and aware of who they are.  It is admirable how carefree (albeit annoying) children can be.  And then the social protocols latch onto them, telling them that this or that thing about them dictates this or that thing about them.  The stereotypes start getting forced into place.  I suppose they have been since birth when the FAAB babies are wrapped up in a pink blanket and the MAAB babies in blue, but neither is all too aware of what the colored cloth clutched in their barely functioning hand means, so it is rather irrelevant to them.

It is saddening to see the once beautiful and smiling faces of the once free children melt every so slowly into a frown of confusion.  Why am I being given a dress?  Why do I have to cut my hair short?  Forcing children to abide by these gender stereotypes (female: pink, dress, long hair, big eyes, weak, feminine) (male: blue, pants, short hair, strong, tough, masculine) is stressful enough, especially if the child does not feel comfortable fitting perfectly within the stereotype, which most do not.  There are people who are different, who felt different before and feel different now, who have suppressed it for so long that they have developed a complex.  A low self-esteem issue, an anger problem, internalized homophobia or transphobia because they have been told time and time again ‘NO!  You are a boy!  Now wipe off that lipstick immediately!’ or ‘NO!  Stop rolling around in the mud!  It is so unladylike!’
Oh god, and the usage of the term “ladylike” is an entirely different issue.

My point is, the suppression of certain tendencies causes internalized issues within the child.  It helps no one to tell them to be a certain way for certain reasons.  Now, not to say that there aren’t children who fall perfectly into the male or female stereotype, because they are, and they are completely comfortable with that and that’s fine.  They never had to repress any sort of controversial queer feeling that gave them a crippling depression and co-dependency issue.  Good for them.  They got out scot-free.
(Now, I must stress that I am talking about queerness, not any other issue.  I understand that there are more situations than simply this that cause such issues.)

Allowing your child to be completely free with themself and grow in any way they like is terribly beneficial to all parties.  Let the child dictate their own growth instead of being pulled along a much different path by a chain.  Freedom is the best parenting technique.