radiobutton checkedchange事件在加载时激发

为什么加载单选按钮时会触发此事件？有办法防止这种情况发生吗？代码如下：

        // 
        // radioButton1
        // 
        this.radioButton1.AutoSize = true;
        this.radioButton1.Location = new System.Drawing.Point(6, 19);
        this.radioButton1.Name = "radioButton1";
        this.radioButton1.Size = new System.Drawing.Size(75, 17);
        this.radioButton1.TabIndex = 0;
        this.radioButton1.TabStop = true;
        this.radioButton1.Text = "You guess";
        this.radioButton1.UseVisualStyleBackColor = true;
        this.radioButton1.CheckedChanged += new System.EventHandler(this.radioButton1_CheckedChanged);
        this.groupBox1.Controls.Add(this.radioButton1);
        public System.Windows.Forms.RadioButton radioButton1;