Sex, whether it be anal, vaginal or oral, MUST ALWAYS be consensual.

I am a survivor of a non-consensual prostate exam by a male doctor. (The correct procedure, in my book, is, you say to the patient, "I just need to digitally examine the prostate to check the size. What that involves is me inserting a gloved finger into the anus. It may be a bit uncomfortable. but I will do my best to minimise discomfort. If, at any point, you want me to stop, just say so, and I will." NOT, to pull the patient's pants down, put on a glove and put lube on it and tell them to lie on their side and say, "Bit uncomfortable."). I am also a sexual abuse survivor, despite it not being penetrative. I would say to any doctor, or medical student, NEVER ASSUME that a male patient will be okay with a rough, blokey attitude towards a prostate exam. You could be performing one on a sex abuse survivor!

I do say, though, that sex is a personal thing. I wouldn't choose to have anal sex with a woman. When I had a girlfriend, many years ago, I could not consider sex if she lay on her front.