How could Reverend Mother Gaius Helen Mohiam be the ((great)grand)mother of people with other/genetic memories, but nobody remembers hers?

Question

In Frank Herbert's Children of Dune, Leto (the later God-emperor) tells Jessica¹:

They know you’re a Harkonnen! It’ll be in their breeding records: Jessica out of Tanidia Nerus by the Baron Vladimir Harkonnen. That record accidentally made public would pull your teeth to—

Jessica already should know this. As a reverend mother she should be able to peruse the memories of her female predecessors. Later in the book she considers the need and (im)possibility of testing of her granddaughter Ghanima: "There was no way to send the pre-born before a Reverend Mother Gaius Helen Mohiam"

In the much later published prequels by (by Brian Herbert and Kevin Anderson) Mohiam is put forward as the mother of Jessica, and this is supposed to be in the older Dune Encyclopedia as well, as mentioned on Wikipedia.

I find this hookup unconvincing. Would Jessica not have known that Mohiam was her mother based on the memories she would be able to access after having gone through the spice agony? Or did I skip some plausible explanation for that?

And if Jessica would not know, then Alia should know as a pre-born. And when she and Mohiam meet in Dune Messiah no mention is made of this realisation by Alia (who did know who her father was when she killed the baron). In Dune Messiah the encounter is described with:

The Reverend Mother refused to look at Alia, but the words burned in her mind. Yes, far deeper implications lay here. The sister was an abomination, true, but there could be no denying her status as a Reverend Mother with all the title implied. Gaius Helen Mohiam felt herself in this instant to be not one single person, but all the others who sat like tiny congeries in her memory.

And earlier Mohiam is not so lofty about Jessica:

"That traitorous bitch,” Mohiam said, voice level. “Would I might disown my own hands which trained her.”

Would you say that of your own daughter, or if you had to, would you not regret having given birth to her, above training her, and complain about that.

Reverend Mother Gaius Helen Mohiam is mother, grandmother and great-grandmother of several people with other/genetic memory and nobody remembers her, not even while meeting her. Mohiam never seems to think of those people as her "offspring" in the original books².

Did I miss any hints in the original books about Mohiam being the same as Tanidia Nerus?
Is there any explanation in the original books, about why none of the people who should know (Jessica, Alia, Leto II, Ghanima, Paul?) ever comment on this "fact". Or is it just the simple case where Mohiam adapt that name after giving birth to Jessica (so it would not be transferable in memory), and would that be enough to hide her identity³?

¹ _{Page 93 of the NEL paperback version. In the chapter starting with "And he saw a vision of armor"}
² _{Those written by Frank Herbert}
³ _{IIRC the prequels already call her Mohiam before her encounters with the Baron, so that could not be an explanation when observing the extended series.}

Answer 1

The nature of Other Memory changed over the course of the books - I'm not sure Frank intended it, or even noticed. Originally, in Dune, OM is only for memories specifically passed over during the spice agony process that changes someone into a Reverend Mother: the description of Jessica has her receiving the memories from the previous RMs of Sietch Tabr, but nothing about the memories of her ancestors.

In Dune Messiah, Alia was depicted as having gained access to her ancestral memories as a result of being pre-born, and Leto and Ghanima similarly in Children of Dune, but still normal Reverend Mothers such as Jessica are not shown to have these memories.

It is only in the later books, Heretics and Chapter House, that we actually see normal RMs with access to ancestral memories. One possible way of explaining this would be to theorize that this is a specifically Atreides ability: we know that all the RMs we meet in those books have the Atreides genes, in order to hide from prescience, and this could be another ability passed alongside that. However, this is pure speculation as it is not explained in the books.

This is all quite separate from the question of whether GHM actually was Jessica's mother, or whether - like so many things - Brian and Anderson just made it up and didn't care that it wasn't consistent with existing canon, which seems more likely.

Answer 2

It's said several times throughout the series that all memories are not open to every Reverend Mother all of the time. Each memory persona has control and is the one that blocks the access, not the carrier. Teg judges Odrade in HOD, "....with full memories on the female side!" This is a rarity among Reverend Mothers.

It would seem that each female in Other Memory would judge when to open the doors. Can this person handle my memories? Are my experiences relevant enough to risk a compromise? Valorum, in the post above, refers to OM being "top-secret classification."

Also, the Sisters constantly warned of traveling too far within Other Memory; it was dangerous and the risk or threat of possession was always there.

If Jessica knew all of her female memory personas, it would have changed the course of the Sisterhood's long-term breeding plan. The Sisterhood were a phenomena in that they worked together, dead or alive, for a very singular purpose.

Answer 3

You asked about RM Mohiam being the direct ancestor. The original series offered nothing to confirm it. The first time it's mentioned is in the Dune Encyclopedia which was not written by FH but was sanctioned by him. It's actually a pretty good read.

However, I could never reconcile that supposed relationship. What does it add to the story? Nothing. Jessica really was a wild card.

Perhaps Frank left that a secret just to give us something to talk about. You think he was prescient? I wonder if Leto II is the real Frank Herbert, eh?

Answer 4

There's no justification for this in Herbert's books and any books published after Herbert's death are in my view just attempts to cash in and should be dismissed.