Congrats on Miss Rainbow and Mr. Spike. As you've discovered they can also have Mohawk boys (as well as blue-hair girls) in addition to rainbow-hair girls and spikey boys. They can also have others further up the head chart (for this couple they would be considered 'rare children'). For the purposes of this game, rare children are basically those that are born outside of the heads between the parents on the heads chart. Does that make any sense?

Hey, would you like me to fix you up an X2Y1 map so that the entire wall by that stairway is crimson?
*Update* I went ahead and did you up a map and PM-ed it to you.
-MissKathy