I come from China and was born abroad. What nationality is this?

The two people you mentioned are both Malaysian nationals.

Ancestral origin is only blood relationship, nationality is legal relationship, and a person can change many nationalities in his life. But a person's ancestral home cannot be changed within several generations.

Nationality has nothing to do with birthplace. A person's first nationality is usually the place of birth, but he can give up this nationality and apply for another nationality. Just like the law in China, when you have another nationality, your China nationality is revoked.