Gain stats through performing some actions (preety much just like skills level up right now).
STR: Chopping down trees, melee fightning, digging holes, harvesting crops, etc.
DEX: Fixing clothes, crafting items, shooting, dodging attacks, etc.
INT: Reading books, hotwiring cars, hacking computers, defusing bombs, etc.
PER: Finding traps, aiming, etc.
Im not programmer, but I guess this might be implemented like StatsThroughSkills- making 4 hidden skills with no books and set them to get exp from performing certain actions only. IMHO this might give more natural stat growth than reading books to get 9th level in all skills and get +10 all stats from that…