What's the nature of personal identity?

个人的同一性的本质是什么？

PERSONAL identity is a tightly policed business.

个人身份是很严格的警政业务。

Personality is the key to personal identity.

人格是个人认同感的关键。

But if it's me, what's the key to personal identity?

但如果那是我，那么个人认同感的关键是什么？

And suppose the soul is the key to personal identity.

假设灵魂就是个人认同感的关键。