It's certainly true for me - that is, if I pick my mom. Active + Active = 8.
My dad would have either been responsive or neutral so I don't know how he fits in. He worked a lot and was on the night shift for years so we didn't see him so much.
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Neutral: avoidant, withdrawn, indifferent, apathetic, absent, reserved, ignoring, neglectful.
Active child vs. Active parent
This scenario is thought to produce Enneagram type 8.
The child and parent experience open conflicts on a regular basis. They both have different agendas and oppose each other, thus giving rise to power struggles and explosive arguments. The Active parent is impatient and intolerant of the child's rebellious nature and tries to impose his will in an authoritarian fashion. The Active child, on the other hand, becomes aggressive, argumentative and persistent in getting his own way. The relationship becomes a sort of battlefield, which is how the child will later perceive the world around him (type 8).
Such a childhood scenario encourages the child to develop a keen eye for spotting other people's weaknesses and a thirst for imposing their will in an overly aggressive fashion. They learn to be assertive, strong and deny their fears and feelings of intimidation. These are the traits they needed to have in order to stand up to their domineering parents and still keep their own Active inborn approach.