In England, especially during the seventeenth century, the mannerisms and characteristics of the people of Holland were held in scorn.
Thus Dutch courage came to mean cowardice; Dutch comfort or Dutch consolation meant “Thank God, it could be worse”; Dutch bargain, a one-sided bargain; Dutch nightingales, frogs.
Even in America “Dutch treat” came to mean a treat in which each person pays his own bill. But the origin of the simile “like a Dutch uncle” is not clear.
It seems to have originated in the United States, but whether the allusion was to the early Dutch colonists of New York or to the Pennsylvania Dutch is uncertain, for the expression did not appear in literature until the early nineteenth century.
The people 111 each of those sections were noted disciplinarians, however, and woe betide the unfortunate child who, having lost its own parents, was obliged to depend upon an uncle as a foster parent.
The expression indicates a merciless tongue lashing, just the reverse of the discipline usually administered by an uncle,