Fråga angående C# och sortering

using System;
using System.Collections.Generic;

namespace PersonTest {
	class Program {
		static void Main(string[] args) {
			List<Person> family = new List<Person>();

			// Create family		firstname	lastname	age		weight(kg)	height(cm)
			family.Add(new Person(	"Fralia",	"Hansson",	44,		76.2f,		168.4f		)); // Married to Murphy but keeping her last name.
			family.Add(new Person(	"Murphy",	"Smith",	48,		92.6f,		185.3f		));
			family.Add(new Person(	"Frank",	"Wesson",	20,		65.8f,		180.1f		));	// Married taking another last name.
			family.Add(new Person(	"Elisa",	"Smith",	19,		70.5f,		176.2f		));
			family.Add(new Person(	"Mark",		"Smith",	12,		58.3f,		129.4f		));
			family.Add(new Person(	"Hank",		"Smith",	10,		49.9f,		124.6f		));
			family.Add(new Person(	"Linda",	"Smith",	6,		41.7f,		85.8f		));

			// Sort family by firstname.
			Console.WriteLine("Sorted by first name:");
			family.Sort((Person a, Person b) => a.FirstName.CompareTo(b.FirstName));
			ListFamily(family);

			// Sort family by lastname.
			Console.WriteLine("Sorted by last name:");
			family.Sort((Person a, Person b) => a.LastName.CompareTo(b.LastName));
			ListFamily(family);

			// Sort family by age.
			Console.WriteLine("Sorted by age:");
			family.Sort((Person a, Person b) => a.Age.CompareTo(b.Age));
			ListFamily(family);

			// Sort family by age descending.
			Console.WriteLine("Sorted by age (descending):");
			family.Sort((Person a, Person b) => -a.Age.CompareTo(b.Age));
			ListFamily(family);

			Console.WriteLine();
			Console.WriteLine("Press any key to continue!");
			Console.ReadKey();
		}

		static void ListFamily(List<Person> family) {
			Console.WriteLine("{0,-25}{1,-5}{2, -8}{3}", "Name", "Age", "Height", "Weight");
			foreach (Person person in family)
				Console.WriteLine(person.ToString());
			Console.WriteLine();
		}
	}

	class Person : IComparable {
		private string firstName;
		private string lastName;
		private int age;
		private float height;		// In cm.
		private float weight;		// In kg.
		// ... More variable declarations.

		public string FirstName { get { return firstName; } }
		public string LastName { get { return lastName; } }
		public int Age { get { return age; } }
		public float Height { get { return height; } }
		public float Weight { get { return weight; } }
		public string FullName {
			get { return string.Join(" ", firstName, lastName); }
		}

		// Constructor
		public Person(string firstName, string lastName, int age, float weight, float height) {
			this.firstName = firstName;
			this.lastName = lastName;
			this.age = age;
			this.height = height;
			this.weight = weight;
		}

		// Will increase the persons age by one.
		public void HaveABirthday() {
			age++;
		}

		// Custom formatted spaced string describing this person.
		public override string ToString() {
			return String.Format("{0,-25}{1,-5}{2, -8}{3}", FullName, Age, Height, Weight);
		}

		// Compare one person to another, we sort by fullname.
		// If the "person" we compare to isn't actually a person we sort our person before the invalid person.
		public int CompareTo(object person) {
			if (person.GetType() != typeof(Person))
				return -1;
			return FullName.CompareTo(((Person)person).FullName);
		}

		// Compare function, in this case we compare the two provided objects to eachother instead of each person to person class.
		public int CompareTo(IComparable a, IComparable b) {
			return a.CompareTo(b);
		}
	}
}