I wasn't aware that the state had an interest in vetting the genetic compatability of potential mates. Should the same logic be applied to two unrelated people whose children would have a genetic propensity for dwarfism, or albanism?
Well the difference is that the twins didn't know they were twins. I don't know anything about the potential genetic problems, but I do think that finding out you had a twin after having falen in love and married them would be pretty rubbish.
Having said that I'm not sure how making it easier to trace your real parents would have prevented this incident - they did find out after all, it was just a bit late at that point!