Basis: In the clone spell, it states clearly that
The clone is physically identical to the original and has the same personality, memories, and abilities, but none of the original’s equipment.
while simulacrum does not have this text. Simulacrum does state, however, that
Otherwise, the illusion uses all the statistics of the creature it duplicates, except that it is a construct.
The 5e SRD definition of "statistics" also refers to that as its "stat block", which consists of features like its type, race, ability scores, features, and notably, its alignment. And according to the suggested post (What all is included in a creature's game statistics?), it only makes mention of alignment without addressing personality or memories and does not provide me with a satisfactorily specific answer.
By the language of clone and true polymorph as examples, does a sim'd creature's statblock include its current knowledge/memories and personality?
The Know question's top answer states that simulacra cannot imitate the target convincingly, which means that they lack the knowledge and personality of the target: a body with no brain, so to speak. The Behave question's top answer states that "if the creature you copied was fiercely independent and highly intelligent . . . and you told it to 'act natural', it would do so," which implies that its personality and at least some memories transfer over.
I'm starting to think this one may be just up to complete interpretation.
– Codex Sep 01 '19 at 03:53