The Blood Code was a part of Snivvian genetics that resulted in each birthing producing one male and one female child. However a flaw in the Blood Code sometimes resulted in male twins being born. The occurrence was rare, with only two hundred documented cases in two millennia. One of the male twins would have a genetic flaw that had a 33% chance they would develop sociopathic tendencies. The Snivvians eventually used genetic engineering to stabilize the Blood Code and prevent twin male births.[1]
Appearances
"Spare Parts" — Star Wars Adventure Journal 11 (reprinted in Hyperspace: The Official Star Wars Fan Club) (Mentioned only)