The important thing is the animus thingy in the game uses unspecified technology, if you have a device which it is not specified how it works or what it actually does it there is no reason why it cannot somehow extract your ancestors past memories, because as it is not specified how it works it could theoretically do anything. Secndly the idea of memories being stored in genetics is probably a bit wacky and I dont think it could ever be the case to the degree in this game, however our memories must be partly chemical and biological (otherwise how could they exist? memories arent just ieces of air), and if memories are biological as is really the only scientific explanation, there must be genetic coding for them, it this coding could be discovered in theroy it would be possible to discover memories, but I doubt they could ever be made visual, and would be purely biological in the sense that for instance they could tell us that at the age of 45 Joe Smith had an increse in his blood sugar levels.