2199 The fourth commandment is addressed expressly to children in their relationship to their father and mother, because this relationship is the most universal. It likewise concerns the ties of kinship between members of the extended family. It requires honor, affection, and gratitude toward elders and ancestors. Finally, it extends to the duties of pupils to teachers, employees to employers, subordinates to leaders, citizens to their country, and to those who administer or govern it.
2215 Respect for parents (filial piety) derives from gratitude toward those who, by the gift of life, their love and their work, have brought their children into the world and enabled them to grow in stature, wisdom, and grace. "With all your heart honor your father, and do not forget the birth pangs of your mother. Remember that through your parents you were born; what can you give back to them that equals their gift to you?"19
2216 Filial respect is shown by true docility and obedience. "My son, keep your father's commandment, and forsake not your mother's teaching. . . . When you walk, they will lead you; when you lie down, they will watch over you; and when you awake, they will talk with you."20 "A wise son hears his father's instruction, but a scoffer does not listen to rebuke."21
The catechism goes on after 2216 to say a lot more about the duties of grown children. Here is the link to further reading on this: