The term "inclination" can have multiple meanings. To understand what causes it, we need to know what context you're referring to. Please clarify what you mean by "inclination."

For example, are you asking about:

* Inclination of a plane: This refers to the angle of a surface relative to the horizontal. The cause of this inclination is often geological processes like tectonic uplift, erosion, or the deposition of sediment.

* Inclination of a magnetic field: This refers to the angle between the Earth's magnetic field lines and the horizontal. The cause of this inclination is Earth's magnetic field, which is generated by the movement of molten iron in the Earth's core.

* Inclination of an orbit: This refers to the angle between an orbit's plane and the Earth's equatorial plane. The cause of this inclination is the gravitational influence of other celestial bodies, particularly the Sun and the Moon.

* Inclination as a personality trait: This refers to a person's tendency to favor or prefer something. The causes of this inclination are complex and involve genetics, environment, personal experiences, and cultural influences.

Once you specify what type of inclination you are interested in, I can provide a more detailed and accurate answer.