The four parts of the above excerpt from W. W. Jacobs's "The Monkey's Paw" which shows that the White family doubts the Major's story are:
1.) "Sounds like the 'Arabian Nights,'” said Mrs. White, as she rose and began to set the supper. "Don't you think you might wish for four pairs of hands for me."
2.) "If the tale about the monkey's paw is not more truthful than those he has been telling us," said Herbert, as the door closed behind their guest, just in time to catch the last train, "we shan't make much out of it."
3.) "Likely," said Herbert, with pretended horror. "Why, we're going to be rich, and famous and happy. Wish to be an emperor, father, to begin with; then you can't be henpecked."
4.) Mr. White took the paw from his pocket and eyed it dubiously. "I don't know what to wish for, and that's a fact," he said, slowly. "It seems to me I've got all I want."
When the Major told the story about the Monkey's paw to the White Family they didn't trust the story. It was for them a tale which can never happen in real life. The conversation between Mr. and Mrs. White regarding the Monkey's paw had a humorous approach. Their son Herbert was also excited to test the reality of the paw and become rich by making a wish from it.