We have a female Basset that is not "fixed" & loves to "hump" my son's leg. How do I stop this?

Well, It is a dominant behavior exhibited for reasons many people do not understand since people have sexual feelings and dogs do not. Once started and let go it is hard to stop. Try to encourage the dog to go fetch something try to re-direct her attentions. Make her get down immediately telling her NO. As far as spaying if you really do love your dog please read this with the intent of how it is written: Your dog as you spoke does not have the basic characteristics of most dogs her type..it may make her cute which I am certain she is but it means that breeding her will only further damage the line in which they are supposed to meet by breeding it should only be done to further the positive aspects in the breed. Could she also have been bred with no thought to her lineage, genetics in heriting traits that may in later years show up as health concerns? Basically a back yard breeder or puppy mill? Her leg length is essentail to carry the long backs and so forth these dogs have and the weight they carry and so forth.What do you have on her genetics for many generations back? Could it not only risk her health but bring more puppies into the world of 10 million homeless that may bring about health issues in this lovely breed of dog? Spaying your dog will reduce cancer types found in many female dogs it could lengthen her life if you LOVE her consider all this and talk to breeders who show dogs and know what is important to the health and welfare of these dogs learn about all you can before attempting puppies who may or may not get the care you give your dog.