I think at one point Yarne was supposed to be the first Taguel you get and Panne would be her daughter, thus Barbarian->Wyvern Knight I guess that after they decided on females being the determining for children that idea was swapped but they did nothing about the conversion.
Patrolling the Awakening message boards almost makes you wish for a nuclear winter...
The kids you listed didn't get a new class. They got a class that their mother passed down to them as their default class.
Yarne gets a random unrelated class and for some reason is the only kid that has to give up something for it. In every other case the only time this happens is if the parent class is gender specific and the child is of the opposite gender.