Genetic Algorithm : How can I make my program more efficient and better than this one?

I Have attempted to simulate evolution in c++. I tried my best to do so. I have learnt a lot of things in the mean time. though, I do believe that there are probably a lot of inefficiency in my program that can be rectified. For example seeding the random generator using time variable, frequent use of size_t variables etc.

Thanks in advance for your effort on my program.

program Links:.

DNA.hpp :http://coliru.stacked-crooked.com/a/2fed586ed7ccf184.

Population.hpp :http://coliru.stacked-crooked.com/a/03e0bc8f87e7b903.

main.cpp :http://coliru.stacked-crooked.com/a/d962f409b5e585d0.