It has been well documented that experiences during childhood carry over into adulthood. As a general rule, positive experiences leave happy memories and encourage development, while negative or bad experiences hamper growth and result in a tentative approach to future dealings.
Children learn as they go along. They pick up things from parents, siblings, friends and the people they meet along the bumpy road to adulthood. Every lesson learned during childhood is a recyclable resource to be drawn upon when needed.
Most kids follow the example they are shown, not the example they are told. If a parent tells a child not to spit while gobbing out of the other side of their mouth, the child will pay little heed to the warning. But if an adult instructs a child to behave at the dinner table, while showing exemplary table manners, the child will follow suit. Kids are smart that way.