The case exemplifies how issue preclusion may bind even the federal government, provided the requirements are met, and further illustrates the flexible application of privity principles.
So privity basically means a close enough relationship to the original party that the law treats you as standing in their shoes for the purposes of res judicata.
The second element is that the parties in the second lawsuit have to be the same as the parties in the first lawsuit, or at least in privity with those parties.
So if someone dies and their site is being handled by an executor, the executor is in privity with the deceased person for any claims related to the estate.
If someone assigns their right to sue to another party, the assignee is generally in privity with the assigner and bound by any prior judgments related to that claim.
So in a later lawsuit, the child might be considered in privity with the parent and bound by the outcome of the earlier case, even though they weren't formally named as a party.