In The Basic Writings of Sigmund Freud, the father of psychoanalysis, and a scientist who spent many years delving into the motivations behind incestuous conduct, wrote that, many fears (of the incest-prone) are learned through conditioning and spread through one situation to another by a process known as stimulus generalization… "A man who fails to achieve an erection grows more fearful until he is totally incapable. He has convinced himself that the reason for his impotency centers around the person of his partner. She can't be trusted, or she is un-thoughtful or selfish and not considerate of his own sexual needs. But a member of his own family displays all the attributes he requires from a sexual partner, an consequently, he discovers that with his own daughter, or own niece, or own aunt, he is not sexually incompetent. To the contrary, he performs lustily and without the slightest fear or reservation. Naturally, he prefers incestuous sex, a relationship where he feels comfortable and secure."

Another reason for the increase in "incest prone" people is the way American raise their children to be overly competitive about sex. This motivations is further explored by Dr. Albert Ellis in his best-selling text, Sex Without Guilt. He states, "… our boys and girls are made to feel that, above all, they must succeed, achieve, win out in the social-sexual game. They must not merely enjoy themselves on their dates and eventually achieve good marriages but they must date the best boy or girl in the neighborhood, be the finest lover for miles around, and have the greatest home and family…"