How many aliens is too many aliens... (ok not a real question but...)

I have MCC set for 8 Vampires, 4 Aliens, and 4 Mermaids. I did this because my game was generating too many Aliens. To me, 12 Aliens was too many, especially after I noticed that it wasn't generating an equal number of Vampires. I also find it strange that Aliens are generated with two or three skills but Vampires typically get none. So, I decided to try to force the game to generate more Vampires. My game was also generating quite a few teen and elder Mermaids that I had no use for so I set the maximum limit to 4.