I understand what mixie's saying here. I've tried to explain being trans in a similar way before as well.
With friends I just try to be quick and simple. but I'm working on coming out to my grandparents, who mean a lot to me. So I wanted them to fully understand this about me.
They didn't know anything about transgendered people. And I was afraid that they would think it was a choice. So I first told them about people born intersex, and the parents sometimes think they have to chose the baby's gender/sex. My grandparents actually saw the Law and Order SVU episode that had an intersex boy in it, roughly based on a true story too.
So after I explained to my parents about intersex people (which they exclaimed, "Oh, you mean hermaphrodites!" and I facepamled, lol)
Then I told them about transgendered people by saying, "And sometimes people are born with genitalia that appear perfectly normal and fine, but the child still grows up insisting he or she is a different gender than we thought.
And my grandparents, who very much hate gay people, were actually very sympathetic to intersexed and transgendered people.
So I do think that explaining transgenders by starting off with explaining the intersex condition can help people see how it's not a choice.
But I do also understand the importance of explaining/including the fact that being transgendered is different for everyone. And there is no one way or right way.
I once went to a seminar through my high school's GSA where a transwoman came up to explain/educate us about transgenders. But I didn't like the way she did it, because she explained how it was for her. She said that she is only part-time female, and half the time goes out dressed as male. (She was MAAB) And that for her it was like a fetish or sexual related for why she cross dressed. But she called herself transgendered as well.
While her way of being transgendered is completely valid, I personally didn't think she put enough emphasis on how that is NOT what it means to be transgendered for everyone else. I was afraid that some people walked away from that seminar thinking that being transgendered is a fetish for everyone.