I'm wondering about this for a while and I decided to ask here maybe I can find answer
I know that the hidden traits are decided upon rezzing (for first time) the box because I heard from CS at Kittycats group that if you have a special edition (I think any starter) then new traits were released, that kitty can hide the new traits if you never rezzed it before releasing them, but not if rezzed and not unpacked.
But what about gender? is it decided upon rezzing or birth (unpacking)?, I'm asking because I notice some patterns, like I get like 3 or 4 females (sometimes more) before I get a male, so maybe I can delay either mating or unpacking for some lines that always give me females when I need males, but dunno which to do. Of course it would never be accurate but it is really frustrating at times to get the wrong gender every week from the same line.
Gender, upon rezzing or unpacking? 
