With faith and sacrifice, Mary and Joseph overcame their fears and made a covenant with God and each other to raise Jesus. This is an important reminder to all Christians that we are, first and foremost, children of God. God entrusts parents with the duty to care for his children, just as Mary and Joseph cared for His Son. Catholic families today make the same covenant that God asked of Mary and Joseph. In the sacrament of marriage, the couple makes solemn promises to give themselves to each other and accept each other, and of love, conjugal respect, and fidelity until death.
Family grows from that covenant.
The promise of a man and woman to work for the good of both, and the good of each, then becomes a promise to work for the good of the children. The Church's teachings on marriage and family also apply in adoption. When a child is abandoned, orphaned or born to parents who decide that they are unable to make and fulfill a promise to God about the care of the child, adoption can be the best alternative. The responsibility then of the adoptive parents is to work for the good of the child, not simply in the physical or economic dimensions, but also in the spiritual one. The creation of a Christian family is not a function of biology.