genetic programming

In artificial intelligence, genetic programming (GP) is an evolutionary algorithm-based methodology inspired by biological evolution to find computer programs that perform a user-defined task. Essentially GP is a set of instructions and a fitness function to measure how well a computer has performed a task. It is a specialization of genetic algorithms (GA) where each individual is a computer program. It is a machine learning technique used to optimize a population of computer programs according to a fitness landscape determined by a program's ability to perform a given computational task.

Is this really a real thing? how do you even generate and mutate programs?

It must piss you off, OP, that nobody answered your question.  GP can be most easily be done with LISP, but really any language can be used that can be represented as a tree.  Then trees can trade branches or nodes to mimic biological reproduction.