Erik Erikson was a German born psychologist who developed the popular idea of normative developmental stages that we go through as we age. Although, it should be noted that these stages were developed based on his experiences with White Euro-American theory and peoples and therefore may not apply to all peoples and cultures.
According to Erikson, one of the core developmental tasks of adolescence is the development of an identity. It is normative during this time (ages 12-18) that teens try on different personas, different interests, etc. as they figure out what fits for them.
But what about those who do not grow up in an affirming or even safe environment, what then? Often there is the creation of a false self, or multiple false selves, and a suppression in figuring out exactly who they are.
This can happen when a child knows that they are trans, or non-binary, or in some way under the LGBTQIA+ umbrella. In these situations they may have a vague or more certain sense of their gender or sexuality because it is helped defined by the resistance it comes up against. But other aspects of their identity may be less firm or formed.
This can also happen when a child grows up in a toxic, neglectful, or abusive homes. In these environments, kids learn to be what they need to be to survive the situation. All of their time and energy is put into survival and so very little is left over for more complex developmental tasks such as learning who they are, what they really like, and what their own hopes and dreams are.
Often I find that people coming into therapy with this type of history often don’t know themselves very well. They do not know what they like, what they want, etc. So we begin by helping them work to know and understand themselves so that they can decide who they are and force the world to deal with them.