Nice kata.

Found a small typo.

towerCombination(3) return 6, because only the following possibilities can be achieved.
should be
towerCombination(3) returns 6, because only the following possibilities can be achieved.

That was hard! Nice job with the kata.

One small suggestion that I have is to improve the error messages for failed test cases. Took me a while to figure some of them out, such as "Before method called invoking P1."

That was fun. Haven't done anything involving genetic algorithms before, so this was a fun learning experience for me. Thanks!

I did run into one issue, however.

    GeneticAlgorithm.prototype.run = function(fitness, length, p_c, p_m, iterations) {
      console.log(iterations);
    };

prints out undefined (atleast on the first test).