Instincts as explanations of behavior have lost their popularity in psychology. The reason:

The list of possible instincts became too long.

Different instincts appeared contradictory in their explanations of behavior.

Explanation:

Instinct: In psychology, the term instinct refers to the term that describes or explains a specific set of an individual's behaviors that are set in motion as well as are unlearned as a consequence of few triggers related to the environment. It can also be defined in terms of motivation as instincts can occur in an organism's response to specific needs to satisfy a few internal drives for survival.