Just for fun. I know DNA doesn't work this way but the way the sequence 'mutates' over generations is interesting? Pretty slow when the population hits a million :-}

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;

namespace ConsoleApplication8
{
    class Program
    {
        static readonly List<Person> Population = new List<Person>(); 
        static Random r = new Random();
        static void Main(string[] args)
        {

            var adam = new Person( new string('0',256),Sex.Male);
            var eve = new Person( new string('1',256),Sex.Female);
            Population.Add(adam);
            Population.Add(eve);
            try
            {
                Breed();
            }
            catch (Exception ex)
            {
                Console.WriteLine(string.Format("World is full. Population is {0}",Population.Count));
                Console.ReadLine();
            }
        }
 
        static void Breed()
        {
            var females = Population.Where(x => x.Sex == Sex.Female).ToArray();
            Console.WriteLine(String.Format("Females:{0} Males:{1}",females.Count(), Population.Count()-females.Count()));

            List<Person> children = new List<Person>();
            foreach (Person male in Population.AsParallel().WithExecutionMode(ParallelExecutionMode.ForceParallelism).Where(x => x.Sex == Sex.Male))
            {
                children.Add(male + females.Skip(r.Next(0, females.Count())).Take(1).First());
            }
            Population.AddRange(children);
            Console.WriteLine(string.Format("Memory used: {0}Mb",Math.Round((double)Process.GetCurrentProcess().PrivateMemorySize64/1048576)));
            Breed();
        }
    }

    public struct Person
    {
        private readonly string _dna;
        public Sex Sex;
        private static Random r = new Random();
        public Person(string dna,Sex sex)
        {
            _dna = dna;
            Sex = sex;
        }

        public static Person operator +(Person m, Person f)
        {
            var result = new char[256];
            int mStart = 0;
            int fStart = 128;
            for (var x = 0; x < 256; x += 2)
            {
                result[x] = m._dna[mStart++];
                result[x + 1] = f._dna[fStart++];
            }
            return new Person(new String(result), (Sex)Enum.GetValues(typeof(Sex)).GetValue(r.Next(2)));
        }
    }

    public enum Sex
    {
        Male,
        Female
    }
}