Thanks for your query, albeit unique.
High butt-crack is not common. But this can occur due to an extra amount of fat in this location, sometimes is seen in some families as a genetic carry-on phenomenon.
Rarely possible due to anatomical variation.
I would advise you to see a General Surgeon or so for a clinical evaluation, physical examination, and investigations such as CT scan or MRI to decide the reason and then get a reference for the respective Surgeon if this can be reduced to your choice or not.
This is possible.
I hope this answer helps you to get a proper diagnosis and to explore the possibility to have it corrected to your expectations.
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.