Parents, until a certain age, your children believe that everything you say and do is right and normal. No one has more to say about the cultural and moral realities about children than parents. You are their truth...until a certain age.
And then there is an age when children can determine truth without you. This is entirely a good thing, a developmental necessity. What you hope as a parent is that when your child learns to determine truth without you, that what you have done up until that point still looks like truth to the child. If your parenting has been untrue in the early years, the children will likely spend the rest of his or her life unlearning you. The process of unlearning a person is painful for all involved and is likely to have poor relational outcomes.
Now, there is hope for parents who have done poorly when their children were younger. Own the wrongs. Not always, but often, when children become adults, they can forgive their parents wrongs when the parent owns those wrongs. Parents who insist that they were great parents when they were not and do not admit their wrongs OR parents who give up to their wrongs and don't even try to change are less likely to find forgiveness.
Here's the take away message: In the early years of childhood, parents are truth. In the later years of childhood and into adulthood, parents are compared to independent ideas of truth. Gross mismatches are damaging. But no matter how bad things have become, there is always redemption in seeking to be a truer person.