I just wonder how they manage to muck up the DNA in the first place!
What I've heard (and seems to be borne out by the evidence) is that the premade characters evolved as the game did. So the earliest-made ones (some of Veronaville, and some of Strangetown) feature lines of DNA that were removed from the final version of the game. Originally they were going to code for far more features than made it into the game.
I suppose Maxis thought that leaving in extra, obsolete lines of DNA wouldn't do any harm, or they just plain forgot. (I'm not sure that the extra lines
do do any harm, but I thought it best to remove them if you're editing DNA anyway). Also, they honestly didn't know about the crashing problem with premade characters, only with people who'd deliberately unlocked the mannequin skin (which does not exist in baby form as you can't buy clothes for babies, and is not meant for use by sims) - I and some other people got into an argument with Maxoid Tom at MTS2 about this
.
Hmm if Vidcund Curious was supposed to have missing DNA, then why did the Vidcund in my game have children (both alien baby and a baby with his wife) normally, without lock-ups? Though now I remember that the alien baby that he did have had face problems...Poor Boba Fett, his alien face got fixed by not appearing at all...
Though I don't know if that was due to genetics or something else...
It's random whether the crash happens or not, and if you have the latest patch (the Uni/NL patch), the problem is fixed. The crash occurred at the point of birth
if the game was unable to assign a skintone to the newly-created baby. This could happen if one of the parents had lines of missing DNA for "Skintone to be passed on", which many of the premade Strangetown characters do. Even then, because each parent should have 2 lines of DNA for skintone, and the game can choose any 1 of these 4 for the newborn child (there are some complications, such as if the parents have wildly different skin colours, but this will do as a simple explanation), it's possible that you could never see a crash.