The concept that parenting is somehow innate is rubbish. Parenting requires skills that we learn by seeking out knowledge from those who have more experience and wisdom than we do, and practicing faithfully what we learn.
That, some good intuition and a stick of gum will get you far.
Some folks gain experience by tending to younger brothers and sisters, or even ailing parents or grandparents. Others babysit in their teens and '20s to gain experience with children. Even others work in childcare or school settings where they acclimate to the ways of children. But, those who are raised in smaller families, or who work at jobs that don't involve interaction with children, don't naturally develop those skills. It doesn't mean that they can't, it just means that they might appear for the job as parent without any of the skills required.
So, when you've determined that you or your co-parent fits that bill and has no real experience or skill set for raising children in a sane and healthy manner, it's time to get some help!
There are a wide variety of books on parenting that can be great resources. Some even come with workbooks. And, for those of you who might not learn best from books, there are also some terrific courses for learning parenting skills. My personal favorite is a course taught in workshop format (all over the United States), that actually comes with a book and a workbook! It's called Redirecting Children's Behavior, and it provides a remarkably easy set of directions for raising competent, terrific little people! Check your local bookstore or Amazon for the books, or simply use any Internet search engine to locate a workshop near you! Your children will thank you for doing so!