There is no indication that Dagny's parents failed in their parenting: they were kind, loving, and did not stand in her way or attempt to change her decisions. There is no fuel here for a Freudian interpretation of Dagny's character, such as, 'her drive to achieve is merely the attempt to earn the love she wanted but was denied as a child.' Greatness, in Rand's heroes, is not the attempt to compensate for some shortcoming; it is an expression of values, not an expression of their absence.
Dagny's father is mentioned in:
Section132 Section152