That is your English nerve.

It deserves all that is said of it." Mr.Mafferton looked at me suspiciously.
"I fancy you must be joking," he said.
He sometimes complained that the great bar to his observation of the American character was the American sense of humour.

It was one of the things he had made a note of, as interfering with the intelligent stranger's enjoyment of the country.
"I suppose," I replied reproachfully, "you never pause to think how unkind a suspicion like that is?
When one _wishes_ to be taken seriously." "I fear I do not," Mr.Mafferton confessed.

"Perhaps I jump rather hastily to conclusions sometimes.

It's a family trait.