Can anybody tell me the origins of this expression?

I found this at this site.

It is a bit risque, so cover your eyes before you read it

Quote:

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The origin of the expression 'how's your father' can be traced back to Victorian times. In those days any man with a daughter was so protective of her virtue that he would take extraordinary measures to safeguard it. Unmarried girls would be kept within the bosom of their family as much as possible, chaperoned on excursions, and on those occasions when they were let out of bounds for social events, their fathers would often accompany them discreetly by hiding underneath their voluminous skirts ready to pounce on any man who transgressed the bounds of propriety - see diagrams.

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Let's just hope the girls didn't eat brussel sprouts prior to their social engagements.

And, why would that be, Sue (insert innocent look here). Would they cause a condition that's commonly referred to in books but that you don't agree with the definition of?

It could give it the meaning which you had attributed to it!