In my case, Hairy butt---check Deep cleft---check Uncleanliness--- No, I am very clean when it comes to my body. Hereditary---No. As far as i know, i am the first to have it in my family. Had acne as a kid---check (the acne on my face is gone now. But I have occasional pimples on my back) Overweight---check (My bmi is 25 . Indian people's bmi scale says i am obese!!) Sitting for long periods of time----check Other cyst on the body---check(there was one on my left inner thigh, for quite some time now, but it has almost disappeared because of antibiotics i took for the pilonidal abscess) Repeated minor trauma on my tailbone----check (I used to carry a backpack full of books to school, and college too for some time. I distinctively remember the backpack repeatedly hitting me close to the tailbone area whenever i moved around) Major trauma on my tailbone----check (The cyst started bleeding for the first time after i took a long international flight on a crappy airline with bad seats) The highlighted part is what i believe started my pilonidal problem.