Many parts of the character creation (and evolution) process in tabletop games can benefit from rigid rules and game mechanic integration. Features and special backgrounds or occupations can help take a page of numbers and stats and form them into the picture you have in your head–often times by adding new numbers and stats. Robotics, cybernetics, skills and trainings…This is where that comes into play in DE.
Mutations, on the other hand, they aren’t so rigid. They aren’t a skill that you’ve spent time training in, or a certain cybernetic leg modification that you’ve been saving up for to serve a specific purpose. Mutations are unpredictable. They are random. You don’t choose them, they choose you. Some of them can be extremely helpful, sure, but others might work against your “build.” Mutations are dangerous.
With this in mind, Mutations in DE will often times not come with spelled-out rules or statistical changes. Their effects will not necessarily be static. One GM might decide that someone with the Diminutive Hands mutation can’t effectively use melee weapons, while another GM may decide that the character gets a bonus to micro-robotics. A third GM may just decide that your tiny hands make people uncomfortable.
Mutations have purposely been left ambiguous, and their effects might change from situation to situation, character to character, and GM to GM. Some are more specific and grant bonuses or penalties, but even those can come into play in unforseen or random ways. They are the wildcard. The unknown element. The chaos.