30-year history?

Has anyone else noticed that, in their recent (2009) "GNs", Zerby and Kelly have referred to TFI's "30-year history"? As we all know, the group started in 1969, so, as of 2009, that would mean a 40-year history.

I see two possible explanations as to why they are using the 30-year number:
1. They are calling 1979 the "true" start of "The Family"; and/or
2. They are trying to distance themselves from Berg.

Either way, I would have thought that any young group would always exaggerate their numbers (how long they have been around, how many members they have, etc.).