Gender identity places huge expectations on children. Girls should play with dolls, boys with weapons or baseball bats. We mold children into how we think they should be, then we take umbrage when they don't grow up to our expectations. Even worse, these instituted minds become personalities who find ways to fall "short" of the expectations we place on them and we fault them for the rest of their lives.
Who hasn't said to a child, especially a male child, at least one of the following: "Just be a man?" "Don't be a pussy." "Tough it out." "Handle it like a man." "Men don't cry." "Faggot." "You're behaving like a little girl." "Man up." "Grow some balls." "Act like a man." "Stop crying, girls cry." "Enough with the tears."
All of these put downs or chastisements stigmatize children, separating them from finding their own personal emotional level. This kind of false expectation over formulating, malleable minds lead to adolescent and adult unhappiness. And in the formulation stages, contribute to long term psychological problems, even death/suicide.
The following short video does a masterful job of pointing the burden we place on our children. It's worth taking a look from the other side.