From his first psychoanalytic writings to his last, Freud was concerned about the relationship of biological forces, which he called the "bedrock," to human psychology. No such theme was more constant than constitutional bisexuality, which he always believed influenced object choice and the degree of a person's masculinity and femininity. In analysis, one could not penetrate the wish for a penis in females or the repudiation (fear of) femininity in males, because they are the "bedrock," ultimately determined by consitutional bisexuality. This paper suggests that, recent work showing how biological forces can change gender behavior in animals notwithstanding, these fundamental qualities in men and women can be caused by quite nonbiological forces-the family psychodynamics that help shape gender identity in infancy.
Stoller RJ. The "Bedrock" of Masculinity and Femininity: Bisexuality. Arch Gen Psychiatry. 1972;26(3):207-212. doi:10.1001/archpsyc.1972.01750210015002