Pretenders are mutant geniuses with the ability to insinuate themselves into any walk of life, to literally become anyone. This talent apparently has two related but distinct aspects: one is the ability to convincingly reproduce or "simulate" any experience, and correctly analyze the results, as well as feel the emotions involved; the other is the ability to learn and master any skill upon exposure, enabling Pretenders to take on any profession. Their intelligence level is such, that they can pick up a text on surgical procedures and within a week or less, be able to perform surgery without ever having gone to medical school and do it better than people who have. A Pretender could later read up on tactical procedures and become a commander of a strike force.
Both the amygdala and the visual cortex of Pretenders are larger than normal. Those two regions are the pattern-matching wetware of the brain. Within Pretenders, the corpus callosum is also significantly larger than normal. This enables high-speed broadband communication between hemispheres. Their motor neuron nerve axons are much larger than normal. This gives Pretenders faster signal transmission and therefore the speed at which their brains processes information is augmented. Since Pretender gray matter is "underconnected" compared to human norms due to a relative lack of interstitial white matter; isolated cortical modules have been forced to become self-contained and hypereffective; which combined with the enlargement of the amygdala and visual cortex leads to pattern-matching and analytical skills far in excess of the human norm.
Pretenders are omnisavants; their groove extends to pretty much every logical and pattern-matching dimension known to man, and more besides. Their genius is at a level normally beyond human capability and they can even do something that's neurologically impossible for everyone else, they can hold "simultaneous multiple worldviews." This allows them to instantly grasp things that to the ordinary person seems plagued by contradictions, to see things most people have to work out step-by-step.
Further more, the functional efficiency of the ionotropic and metabotropic receptors of Pretenders are significantly enhanced and an increased level of a specific enzymatic output enhances the production of a broad range of neuronal proteins responsible for both short-term and long-term memory, memory capacity, and the analytical purposing of memory. Because of that, Pretenders possess an extraordinarily advanced information storage and retrieval. Their memory retention reaches a level of total recall of any information they are exposed to. This means a Pretender is not only a beyond human level genius, but also an information sponge.