HI welcome to health care magic.........
are not sexually transmitted.
The cyst forms when the duct draining the bartholin glands( normally present) gets blocked and the secretions pent up causing a cyst there.
What causes the block is not known .
Treatment is either they open up the cyst or place a catheter to hel drain the contents of the cyst.
Unfortunately the cyst reappear in majority and there are no drugs or treatment to prevent them from reappearing.
The only thing is to get them removed when they appear.
As its not a sexually transmitted so its not related to sexual activity.