chaiyah;
been a while
i would say oestrus, hunger, and thirst are physiological states; and, what the animal does about each is guided by instinct, or specific 'hardwiring' in the brain reinforced by eons of genetic success.
The instinct simply "says" mate, eat, or drink; then there is also a 'learned' component of how to go about satisfying the various appetites, which comes from familial training, and/or experience.
Instinct is not 'in' the dna, it is in the brain mass, the growth of which has been directed by the dna.
While i would not say i was totally disagreeing with you, sometimes the 'truth' is in the details!