There is no one explanation for the multiple expressions of gender. Rather, many influences shape any individual's self-image and gender presentation.
Among those influences have been advances in both philosophy and psychoanalytic theory. They have each contributed to our understanding of self-image and self-expression in gender. What has resulted is that birth sex has become less normative for about 20% of young adults. Instead, that group presumes that defining how they think about their gender and express it is part of authentic development.
Essential to the responses of psychotherapists, parents, and others is to deepen our capacity for empathy. Advanced empathy skills include reminders that humans live "in time" and that the journey toward maturity and Christian holiness is not instantaneous but gradual and step-by-step. One tool for expanding empathy is to find the courage to acknowledge our fantasies. They can be clues to both our inner needs and motivations along that journey and the journeys of those we know and care about.
Also, as part of accompanying those on their life journey, psychotherapy becomes "Catholic" when evidence-based treatment is linked to the Church's insistence on the centrality of life, the church's sexual morality, our call to holiness, and the belief that to live a happy life requires virtue, courage, and the guidance of the Holy Spirit.
This book reviews the multiple influences on self-image and gender expression. Each chapter includes a couple of connections to the vast treasure trove of Christian anthropological and Catholic psychotherapeutic resources. The forty short chapters include definitions of terms and brief introductions to personality influences.
The book also adds that navigating our developmental journeys involves examining our expectations, loneliness, similarity versus complementarity, genuine self-love, attractions, romance, and intimacy.
Lastly, shaping our desires requires responsibility, virtue, courage, and a commitment to modeling our sexuality on the inner life of the Trinity.