Windham Jokes

Two French brothers were in England, visiting long-lost relatives, their English cousins. Having high tea with Lady Windham, Pierre was making chit-chat: "Tell us about your children, dear cousin."
"Oh," said the Englishwoman, "alas, I have no children."
"I see," piped in Jean-Claude, "you are FRUITLESS."
Seeing the expression on Lady Windham's face, Pierre said, "I think that the proper term is UNBEARABLE."
"Non, non," corrected Jean-Claude, "I've got it now: she's IMPREGNABLE."
The lady winced, and Pierre said, "Perhaps the word we're looking for is INSURMOUNTABLE"
"Voila! I have it," exclaimed Jean-Claude, our dear cousin in INSCRUTABLE!"