Photographic Memory: On the list of enhancements built into people, with the note that it is originally only eidetic short-term, and requires voluntary “fixing” to persist as long-term eidetic memory; it also includes the ability to suppress and erase them on demand. (These to avoid being Cursed With Awesome.) A normal education trains this ability to a very high level.
Also, where externally stored memories count, this is what lifelogs and remembrance agents do.
Genetic Memory: Exists naturally in a few places, of course. That terrestrial biology, et. al., happens to use different storage mechanisms for genetic and memetic information is purely a local quirk, not a law of nature.
But better known is that those wacky bioengineers, the esseli (remember them?) have invented ways of encoding memory information into plasmids, and organs to produce and read them. So, have those built in or, um, retrofitted, and you too can pass your genetic memories around – and, indeed, to your offspring if you think to have them equipped with the same organs.
But they haven’t made it naturally heritable, yet.
The Fog of Ages: This didn’t so much happen to the natural immortals of the setting, but then, the natural immortals weren’t all that natural, having been designed into immortality by one particular group of Precursors, and it is generally believed that a few memory upgrades came with the deal. While it probably would have eventually – well, these days, they’re using offloading extra memory and cognitive processing to the cloud and its ultratech nanocomputronium cores, so it’s unlikely to ever come up in the future.
It can, which is relevant where immortalist proselytizing comes into play, affect people who’ve just taken an immortagen and nothing else, but, well, if it bothers you, they also have this nice catalog full of brain upgrades, memory-management techniques and advertisements for memory-redaction and psychedesign services right here, and they’d be happy to sell you some.