Why does President Trump repeatedly lie about where his father was born?

I just heard in the news that President Trump said his father was born in Germany; whereas, his father was actually born in New York. And I see online that this is at least the fourth occasion on which he has told this particular lie.

Like Trump’s many other lies, this lie is so preposterous and easily checkable that any ordinary explanation just won’t work. And he is not stupid, so why would he do it?

In line with my previous speculation that Trump has multiple personality trait, I wonder if this lie can be attributed to an alternate personality. Keep in mind that multiple personality may be thought of as multiple reality, since each alternate personality has its own view of reality, which, unlike the reality of the host personality, may not be objective reality.

One possibility would be an alternate personality who sincerely believes that his father was born in Germany.

Another possibility would be an alternate personality who is designed to tell momentarily convenient lies in total disregard of later consequences, because it has no sense of the future, and lives purely in the moment.