using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var animals = new List<Animal> {

            new Animal { Name = "Cat", XChromosome = "X", YChromosome = "Y" },

            new Animal { Name = "Bat", XChromosome = "XX", YChromosome = "Y" },

            new Animal { Name = "Dog", XChromosome = "X", YChromosome = "YY" }

        };

        var properties = new List<Properties> {

            new Properties { Name = "Dog", Prop1 = "Bark", Prop2 = "Brown" },

            new Properties { Name = "Mouse", Prop1 = "Pi", Prop2 = "Grey" },

            new Properties { Name = "Cat", Prop1 = "Mew", Prop2 = "Black" },

            new Properties { Name = "Cat", Prop1 = "Moo", Prop2 = "White" }

        };

        var matches = from a in animals

                      join p in properties on a.Name equals p.Name into g

                      from p in g.DefaultIfEmpty()

                      select new {

                         a.Name,

                         a.XChromosome,

                         a.YChromosome,

                         Prop1 = p == null ? null : p.Prop1,

                         Prop2 = p == null ? null : p.Prop2

                      };

        foreach(var match in matches)

        {

            Console.WriteLine("{0} [{1}-{2}]: {3} {4}", match.Name, match.XChromosome, match.YChromosome, match.Prop1, match.Prop2 );

        }

    }

}

​

    public class Animal

    {

        public string Name { get; set; }

        public string XChromosome { get; set; } 

        public string YChromosome { get; set; }

    }

​

public class Properties

{

    public string Name { get; set; } 

    public string Prop1 { get; set; } 

    public string Prop2 { get; set; } 

}