Several of the themes, popular in the old days, that are not seen today, were incest and animal ***. Animals had their own imprint, Pet Books! Dogs, Horses and Donkeys were typical, with titles such as "Wife does Dogs" "Horse Loving Mother" "Donkey R**ed Daughter" etc. There were even a couple featuring goats and one titled "Ape Girl" in which the girl had relations with apes. Then there were combo themes with animals and incest, and not prettied up by using the "step" prefix. These were daughters/sons with fathers/mothers in which a dog or horse also figured. Numerous books featured fathers seducing their teenage daughters or mothers seducing their teenaged sons, sometimes with the entire family ending up having relations with each other or a son bringing his friends home to have relations with his mother - willingly or not! These days it is always a step daughter/father/mother/son over the age of 18 and the poster always seems to feel it necessary to state that "no blood relations had s** with each other. How times have changed!