Marriage Inequality: How will we explain to future generations?

Have you ever stopped and wondered how we'll explain to future generations about marriage inequality?

Seriously.   How?

Student 1: I don't understand.
Teacher: Well people did a lot of things that didn't make sense back then, we've come a long way since--
S1: No, I don't understand how it was enforced.
T: Two people could only get married if they were of opposite sexes.
S1: But how do you enforce that?  Couldn't same sex couples just say they were opposite sexes?
T: Well--
Student 2: Maybe they had a gynecologist and a ... a ... what's a man-part gynecologist called?
T: Urologist (the teacher helpfully says), but--
S2: Yeah, maybe they had a gynecologist and a urologist check out the couple first.
Student 3: But not everyone fits in those categories.
S1: So did they just do genetic testing before you could get a marriage licence?
T: Everyone listen,--
Student 4: Everyone knows that genetic testing is inconclusive at best.  Phenotype and genotype--
Three Students In Bored Unison: are not the same thing.
S2: So did the priest just say, "Drop your pants," and make a best guess?
S3: Not all weddings are preformed religiously.
S2: So did the--
------------S4: city clerk just say, "drop your pants," or something?
T: It really wasn't as complica--
Student 5: I mean with all of the variations in the world how could they ever be sure who was what gender anyway?
T: They only recognized two at the time.
Student 6: (in shock) So were berdaches considered non-people?
T: It wasn't like--
S6: Did they have any rights at all??
T: We're getting off topic h--
S6: They were in America before there was an America.  Before Columbus, before Ericson... how could our ancestors just--
T: They were considered full people.
S6: (defiantly) They just weren't allowed to marry.
T: No, they were allowed to marry it just had to be--
S1: So how did they determine the genders of people applying to be married?
T: Well I think they just--
Student 7: You THINK!?  Don't you KNOW?!

And so on.

I mean seriously, try to imagine explaining to someone who has never known anything but equality how it is we enforced "opposite sex marriage" when, in spite of some thousands of years of trying, we still have yet to figure out how the fuck to define "sex" in a way that actually applies to all situations.