By 'male sexual interactions' you mean having sex with males, I guess. And you are always a female MC. The male starting path just says that you were a male before waking up in the hospital.
As TheGentleMagpie said, most sexual interactions are optional in the meaning that you can escape sexual advances. But the efficiency of escaping depends on many factors so there are moments when you are unable to escape being forced. The probability has been lowered significantly in the latest versions but it's still possible. Generally, as your sister told you, try not to run around half-naked, horny and on drugs in the middle of the night ;)