I never said that hormones were the only influence, in fact I agree that genetics is also important.
Regarding behavior, and specifically the SDN, consider, for example:
The volume of a sexually dimorphic nucleus in the ovine medial preoptic area/anterior hypothalamus varies with sexual partner preference. Endocrinology. 2004
"In addition to a sex difference, we found that the volume of the oSDN was two times greater in female-oriented rams than in male-oriented rams."
Wired on steroids: sexual differentiation of the brain and its role in the expression of sexual partner preferences. Front Endocrinol (Lausanne). 2011
"Development of female-directed partner preference in the male is dependent on exposure of the developing brain to gonadal steroids synthesized during critical periods of sexual differentiation of the central nervous system"
The development of male-oriented behavior in rams. Front Neuroendocrinol. 2011
"Although our understanding of the biological determinants and underlying neural substrates of sexual attraction and mate selection are far from complete, compelling evidence is discussed that supports the idea that neural substrates regulating sexual partner preferences are organized during prenatal development"
Regarding behavior, and specifically the SDN, consider, for example:
The volume of a sexually dimorphic nucleus in the ovine medial preoptic area/anterior hypothalamus varies with sexual partner preference. Endocrinology. 2004
"In addition to a sex difference, we found that the volume of the oSDN was two times greater in female-oriented rams than in male-oriented rams."
Wired on steroids: sexual differentiation of the brain and its role in the expression of sexual partner preferences. Front Endocrinol (Lausanne). 2011
"Development of female-directed partner preference in the male is dependent on exposure of the developing brain to gonadal steroids synthesized during critical periods of sexual differentiation of the central nervous system"
The development of male-oriented behavior in rams. Front Neuroendocrinol. 2011
"Although our understanding of the biological determinants and underlying neural substrates of sexual attraction and mate selection are far from complete, compelling evidence is discussed that supports the idea that neural substrates regulating sexual partner preferences are organized during prenatal development"