To add to Cerberus's excellent answer that all the words have the same Indic root, one can still see English language inscriptions in Scotland where the said wh- words are written qu-. I can only cite personal observation in several churches in Edinburgh and I don't know whether this practice arose from a natural orthography, from a Scottish wish to differentiate oneself from the English, or from a wish to reaffirm Scottish-French solidarity (several of the examples, if I recall correctly, were from the time of Mary Queen of Scots).

To add to Cerberus's excellent answer that all the words have the same Indic root, one can still see English language inscriptions in Scotland where the said wh- words are written qu-. I can only cite personal observation in several churches in Edinburgh and I don't know whether this practice arose from a natural orthography, from a Scottish wish to differentiate oneself from the English, or from a wish to reaffirm Scottish-French solidarity (several of the examples, if I recall correctly, were from the time of Mary Queen of Scots).