Rare, only a few thousand cases of it across known humanity and many of them are far too weak to be of any practical application or use.
Initial experimentation was cruel and violent, nearly all of the first generation of psychics died in labs as humanity learned about this new evolution. Once the nervous system was pinpointed, amplifiers were developed. These tap into the brain and spine and 'extend' the nervous system, increasing a psychic's natural ability.
These amplifiers allow for psychics who would normally be too weak to perform well enough to fulfill the burgeoning roles in society created for humans with this ability. At this time there are only two roles, the much more common dispatcher assignment in Astral Section, and the much rarer deep navigator for the sweepers.
At this time, there is a limit to the number of amplifiers a human can endure and it is tied directly to their natural abilities as a psychic. The returns on an amplifier decrease with each implant and the returns after just one for a weaker psychic are not worth the danger to the human when getting them.
The process of implanting is the installation of ports onto the psychic that allow a neural spike to be plugged into the brain or spine. These spikes then act as a simulated extension of the nervous system, giving the psychic more physical matter with which to generate psychic energy. These ports are currently capable of being installed one in each temple and two at the base of the skull into the spine, totaling to four. Though the secondary spinal implant is currently only in testing.
The fourth implant has yet to be used outside of a lab environment. In field cases, three is the max that has seen viable returns and currently only a handful of psychics are strong enough that a third implant sees enough amplification to be of use. The vast majority of current psychics with implants only have one. The use of two is a fraction of the use of one and the use of three is almost a rounding error in viable hosts.
Nearly all psychics display physical mutations or abnormalities. This stems from the fact that nearly all psychics so far have been born from the result of birth between heavily gene modded parents, typical of the 'spacer' culture class. There are humans whose ancestors were initially heavily modified for early space life where deep space habitats suffered from poor gravity, comfort, and lighting. Often on top of this, parents of psychics usually have further modded themselves, typically for aesthetic reasons.
There has been minor success in producing in-vitro children psychic by heavily modifying the genetics of the donor sperm and egg to replicate typical parents of this nature, but no psychic born this way has shown enough aptitude and strength for their abilities to be applicable in society.
Typically a psychic's physical form is small in nature, and in testing they struggle to build extra muscle or physical prowess. Typically psychics never reach a height beyond 165 cm or 5'5'' and maintain a slight or lean frame. Albinism, vitiligo, and unnatural hair colors are common in psychics, though they are not a symptom of their psionic condition, but a common result of being born from modded parents who pass down these modified genetic traits.
Sharp teeth, odd hair and eye colors, and irregular skin are all mutations that can be passed down from modded parents, it is the slight frame and lack of growth that have been confirmed to be tied with the genetics that expressly display psionic ability.
The most common psychic is a minor empath, allowing them to sense the emotions and feelings of those around them. While this confers a benefit in average social situations, it is not a strong enough ability to be of use beyond that.
A psychic who would be capable of passing the Astral Section dispatcher evaluations typically shows a much stronger empathic ability and minor telepathy. They should be able to sense the mood of many people quickly, read thoughts well enough to pass the Zener card test. When these traits are amplified correctly they can be used to accurately and quickly guide enforcers on manhunt chases through the complex and dense human colonies of sol.
Psychics beyond this level are very rare, but have been showing up more with each generation. The gamut of strength in this level varies greatly but can include physical manifestations such as cryo or pyro kinetics, much stronger empathy such as psycometry, or even varying strengths of telekinesis. Typically the stronger a psychic the more they show a combination of these abilities in various strengths.