Once you peer into the other side of gender, depending on your nature, a transition to a little-explored state-of-being can become inescapable.
This is because, while you can forget facts and details, you cannot erase an understanding.
And if you are generally empathetic, then once you experience something, you cannot help but remain empathetic to those experiencing the same things.
A medically transgender individual(manually hormone-swapped) is not like a cis-male, or a cis-female, or even like an intersex individual(who can be like almost anything).
We more or less understand what cis-males and cis-females are generally like, and intersex people will, unfortunately, never be quite understood, as there is so much possible variance.
But we will eventually understand what trans-male and trans-female people are generally like: what are their strengths and weaknesses vs. other varieties of humans.
Gender, like genetics, is not everything. But it is not nothing, either.
We should neither refuse to draw conclusions based on direct observation, nor rely only on pre-existing notions, when thinking about individuals or groups of people.