An instinct should be differentiated from a reflex response which is a response to stimulus or voluntary action such as skin reaction to pin, needle or any sharp object.
People may be able to modify a stimulated action by seeing it in the brain and recognizing it then stops the action before it takes place consciously or subconsciously in their mind either activated or not. while for animals there is no possibility of stopping their stimulated fixed action pattern once focused on, activated.
A fixed action pattern, in which a very short medium length of sequence of actions are carried out in response to stimulus. This relates to human beings and animals just as a little child sees its mother training and nurturing. it brain, mind, instinct response to the action of its mother training but when the child is separated from it mother and the child has a sibling the child may not recognize or acknowledge it (sibling) as a sibling because the child lacks the training of a mother just like animals.
Sam Alugo's blog 