There are practically no serious epidemiological studies on this topic - a search on nih.gov gives out only a couple of dozen articles over the past 40 years. However, after a person once encounters an unpleasant disease, he begins to look for opportunities to prevent such a disease in the future.
And do not hesitate to talk about ways to prevent hemorrhoids and anal fissures. This is true not only for gays, but for all people. In cities, we often lead an inactive lifestyle. Or vice versa, we lift weights in the gym. There is a great risk of exacerbation of hemorrhoids in women after pregnancy.
Prevention consists in proper bowel movement - preferably in the morning at the same time. Physiologically, it starts better if you drink a glass of water at room temperature right after rising. Observe the hygiene of your body. Eat enough vegetables (fiber). And remember about the physiology of the pelvis. She is shown very well in the hilarious cartoon Squatty Potty - a toilet stand that allows you to do this procedure right.
Logic suggests that microtrauma, microflora disturbance, deterioration of tissue elasticity and increased blood supply to veins will accelerate the onset of this disease.