Just like in real life then :D
If you want to keep it random but still get blue eyed sims, the only thing that comes to my mind is to start a hashtag #blueeyes or something like that on the gallery and people would upload their creations. Then, without a second thought you could just add them to your game, not checking them out at all (or as little a spossible) so you keep the element of surprise.
People can upload entire families (so the kids would grow up and could be also potential matches for your future generations)
I know is still not what you want but it could be fun.