Little joke I found in a YouTube comment someday somewhere (slightly reformulated)

During a visit to queen Elizabeth, Biden asks:

"How is your parliament so effective?"

"Because I pick very smart people for their positions", the queen answers.

She then phones Boris Johnson.

"Boris, answer me. If your mother has a child, and it's not your brother nor sister, who is it?"

"It's me", says Boris.

Back in the US, Biden calls Kamala and asks her the same question.

"I have to think about it and I'll give you my answer soon", she says after thinking for a minute.

At evening, Kamala asks her husband the question.

"That's easy. It's me", he answers.

The following day, Kamala goes confident to the White House.

"Mr. President, I have the answer to your question. The child of my mother who is not my brother nor my sister is... My husband!"

Biden goes mad and, while shaking her shoulders, shouts:

"You idiot! It's Boris Johnson!"