She was only a librarian’s daughter, but boy was she stacked!
She was only a wrestler’s daughter, but she always came through in a clinch!
She was only a telegraph operator’s daughter, but she didit and didit and didit!
She was only a minister’s daughter, but I wouldn’t put anything pastor!
Got any? 
She was only a Hindu’s daughter, but holy cow!
She was only a porn star’s daughter, but boy did she like to have sex quite frequently!
She was only a semiotician’s daughter, but she knew a thing or two about triadic relations.
She was only a glass grinder’s daughter, but was she a spectacle!
I am hoping most of you are too young to know that is older and me and my wife.
She was Bred in Old Kentucky,
But she’s just a Crumb up here.
I found this same game in a 1930 newspaper. They gave you ten examples, and you filled in the blank. Most of them were pretty sappy.
An example of the best one: “She was only a ______ daughter, but she always kneaded the dough.”
She was only a printer’s daughter, but she just wasn’t my type!
She was only the stable man’s daughter
But all the horsemen knew her.
(Oh come on, it’s funny!)
She was only a fisherman’s daughter, but she reeled when she saw my rod.
She was only a hacker’s daughter, but she still knew how to handle hardware problems!
She was only a framers daughter, but she was outstanding in her field.
She was only a stonecutters daughter, but no one took her for granite.
And of course She was only a farmers daughter but she liked to get hammered.
She was only a mortician’s daughter but she nearly killed me!
She was only a communist’s daughter but she sure was classy!
She was only a carpenter’s daughter but she sure gave me wood!
She was only a tobacconist’s daughter, but she’d shag under the counter for half a crown.
Close to this one I know “She was only a fishmonger’s daughter but she lay on the slab and said fillet.”
She was only a plumber’s daughter, but she sure could drain it!
Revised lines from Seinfeld:
She was only a violinist’s daugher but Yo Yo Ma!
She was only a diplomat’s daughter but Butros Butros Galli!
And on the flip side:
He was only a carpener’s son, but he used his 12 inches as a rule!
She was only the fishmonger’s daughter, but she had the wettest plaice in the shop!