Thinking more about 1e I figured it would be a nice option to allow the chance for latent psionics as we did in the old days (I recall having 1 character who rolled the required % number over decades of play). Here are the 5e updated rules.
Psionics are various powers derived from the brain, and they enable characters so endowed to perform in ways which resemble magical abilities. If your DM opts to include psionic abilities in your campaign, they will be determined for humans (and possibly dwarves and halflings) as follows:
Characters with one or more unmodified intelligence, wisdom or charisma ability scores of 16 or higher might have psionic ability. Whether or not this ability is possessed is then determined by a dice roll using percentile dice. Any score of 00 (100%) indicates the ability exists. For each 1 point of intelligence above 16 add 2.5 to the dice roll, for each 1 point of wisdom above 16 add 1.5 to the dice roll, and for each 1 point of charisma above 16 add 0.5 to the dice roll (drop all fractions).
Example: A character has intelligence of 17, wisdom of 12, and charisma of 17. There are 2 1⁄2 points to be added to the psionic potential roll because intelligence is 1 above 16, and 1⁄2 point for charisma 1 above 16, total 2 1⁄2 + 1⁄2 = +3. The dice are rolled, and any score of 97 or greater indicates psionic ability exists in the character.
A character that gains access to psionics may choose one talent from one discipline and has as many power points as levels and no psi limit. You choose these abilities from the Mystic class options.