Three Basic Orientations
The three orientations are an expression of the Law of Three, on which the entire Enneagram concept is based. This law states that there are three kinds of forces that act in the human nature - the Active force, the Responsive force and the Neutral force and that each person is born with a natural preference for one of them.
These three forces are similar to the Hornevian Groups (Assertive, Compliant and Withdrawn respectively), but they are used here in a different context, to describe inborn traits and parental styles rather than established personality.
Here are the associated traits for each basic orientation:
Active: demanding, assertive, bossy, outspoken, intimidating, egocentric, expressive, willful.
Responsive: supportive, responsive, engaging, affectionate, friendly, sympathetic, cooperative.
Neutral: avoidant, withdrawn, indifferent, apathetic, absent, reserved, ignoring, neglectful.
Apparently, each child comes into the world with one of these predefined attitudes toward their environment and each parent will address their children with a certain parenting style, which can be, but isn't necessarily determined by their Enneagram type.
Any Enneagram type can use any of the three orientations to attend to their children. For example - an Enneatype 5 can be a Responsive parent, an Enneatype 8 might use a Neutral approach with their offspring, while an Enneatype 1 may lean towards an Active style. What determines the environmental component of a child's future type is not necessarily the main caretaker's type, but rather their particular approach to relating to the child.