It is true sexual identity as explained in a series of talks by Pope St. John Paul II from 1979-1984. Primarily it stems from the pope's reflections on the Creation stories of Genesis 1-3, Jesus' teaching on marriage and divorce in the Gospels, and Jesus' and St. Paul's teaching on the resurrection of the body throughout the New Testament.
Theology of the Body (TOB) is the term used to describe the theological nature of our bodies, in that since we are made in the 'image and likeness of God' an honest reflection on our human body will lead us to a deeper understanding of God. Our bodies reveal that we are persons made for communion with others in the image of God who is a Trinity of Divine Persons. The Church proclaims that we all wrestle with our identity as male and female, and that this struggle will lead us to God. If we have the eyes to see our bodies in the light of Divine Revelation, we will see nothing short of the divine image when we look in the mirror and at each other.
The vast majority of these lectures were delivered at the normal Wednesday catecheses (teaching sessions) which popes deliver to the thousands of Catholic pilgrims gathered in St. Peter's Square at the Vatican. Although the material is quite heavy at times and deepy theological, John Paul II intended for the Theology of the Body to be understood by all the Catholic faithful.
EWTN has compiled all 129 of the pope's lectures which are available here in English.
For more information, please contact the Office of Marriage and Family Life, Chez Filippini at (850) 435-3553 or firstname.lastname@example.org
The Catechism on Chastity