Desire that’s in our genes (4)
I believe the answer is:
urge
'desire' is the definition.
(thesaurus)
'in our genes' is the wordplay.
'in' says the answer is hidden in the clue.
'URGE' is hidden in the letters of 'our genes'.
'that's' acts as a link.
(Other definitions for urge that I've seen before include "Press to do something" , "Induce; yearning" , "Encourage; impulse" , "Strongly recommend; impulse" , "Capital of Colombia" .)