system
Given the following post, respond as if you're commenting on Reddit:
human
[Blade Runner] How could someone determine if they are a replicant by themselves?

Surely by the end of the film. Deckard must have some suspicions about being a replicant, is there anyway he could find out without getting the test administered?
gpt
Are you asking "for a friend?" 

The following is assuming a Nexus 6 model living freely and independently in the world:

With a properly established personal history and isolated from any outside corroboration, not really. 

If you run into other people and notice suspiciously identical personal experiences among you or if someone has details of your private thoughts, then you might reasonably assume you have a manufactured life. It would be hard to prove either way. Even Deckard is no certainty, depending on which version of his story you heard.

If you die for no apparent reason in your prime, that is also an indicator. At which point it's not terribly important. What's it matter anyway. If your life is so human that no one including yourself knows, who cares? Even with a manufactured past you still live in the now. You feel things, make choices and experience life as it is happening - just like a human.