https://en.wikipedia.org/wiki/Epigenetics_in_learning_and_memory
I'm not sure that memory equates to instincts too well.
Whether in the short or the long of it.
Short, mother does drugs while pregnant, health consequences for that baby.
Long, some humans go somewhere with little sun or much sun.
Skin changes.
In either case, I don't think we'd say we have 'our ancestors 'memories.
Though it is true that our genetics can reflect past roads and actions of our ancestors.
Memory seems more to me something one 'remembers.
Not ability, talent, susceptibility.
If something has a strong talent for being aware to threats because it's parents were in a heavy predator location.
I still would not call such 'memory.
. . .
I think the scope of memory they said in Assassins Creed was science fiction.
Not that I've read any more on the subject of epigenetics than a few webpage skims.
I'm not yet convinced either, that I'd call epigenetic memory, memory.
But if it 'were classified as memory, I don't think there's enough of it, that one could have such detailed memories of past lives.
. . . Though one could argue that in Assassins Creed most of the memory is fake, filling in the blanks by the scientists and person remembering.
. . . But even then, I don't think there'd be 'enough memory (If there 'is any memory) to be useful.
. . .
Maybe a species other than humans,
or if humans were modified could inherit clear memories.
In Warhammer, some space marines can eat people's brains to gain their memories.
. . .
But having a fear of spiders because your great grandfather lived during the poison spider swarm in ages past and was bit a lot,
Isn't the same as being able to remember your great great grandfathers various sense memories or data acquired by great grandfather.
For instance his name, without ever being told, seeing, or reading about it.
. . .
I also don't think you 'remember or have 'memory about something, from indirect nurture consequences.
Parent is abused as child.
Parent abuses you as child.
You do not have 'memories of your parent being abused as a child.
You are 'effected by your parent being abused as a child.
There exists information by your parents 'actions towards you, that they may have been abused.
Still not memory in my view.