c# trait mixins via intefaces and extension methods

Traits.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Traits;

namespace TraitsMixin
{
    //trait Similarity 
    public interface TraitSimilarity {
        Boolean isSimilar(object x);
    }

    public static class TraitSimilarityProvide
    {
        public static Boolean isNotSimilar(this TraitSimilarity trait, object x)
        {
            return !trait.isSimilar(x);
        }
    }
    //end trait Similarity 

    //trait Circle 
    public interface TraitCircle
    {
        int Radius();
        TraitCircle Rotate(int x);
    }

    public static class TraitCircleProvide
    {
        public static int Diameter(this TraitCircle trait)
        {
          return trait.Radius() * 2;
        }
        public static TraitCircle intRevRotate(this TraitCircle trait, int x)
        {
          return trait.Rotate(-x);
        }
    }
    //end trait Circle 

    public class Test : TraitSimilarity, TraitCircle
    {
        public Test(int radius)
        {
            _radius = radius;
        }
        public int _radius;

        public bool isSimilar(object x)
        {
            if (x is Test) return true;
            else return false;
        }

        public int Radius()
        {
            return _radius;
        }

        public TraitCircle Rotate(int x)
        {
            return new Test(_radius);
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var test = new Test(5);
            test.isSimilar(test);
            test.isNotSimilar(test);
            test.Radius();
            test.Rotate(5);
            test.intRevRotate(5);
            test.Diameter();
        }
    }
}