Dynamic Creation of Controls in a questionnaire

I am creating a questionnaire that has its controls dynamically created within a user control. I am hooking the creation of this controls on the usercontrol page_init event.

My question is how can I parse through all the controls on the form and get the user's selected answers? Note also that the questionnaire will have textboxes, radiobuttonlists, dropdowns and other controls. Should I create the controls with their ID as the Question's primary key?

 public void CreateInstanceOf(string controlType, IEnumerable<ANSWER> answers, UserControl userControl)
        {
            var getTypeByStringName = TypeMapper(controlType);
            if (getTypeByStringName != null)
            {
                var newControl = Activator.CreateInstance(TypeMapper(controlType));
                var castedControl = newControl as Control;
                if (castedControl != null)
                {
                    if (castedControl is DropDownList)
                    {
                        var dropDown = castedControl as DropDownList;
                        foreach (var answer in answers)
                        {
                            dropDown.Items.Add(new ListItem {Text = answer.ANSWER1, Value = answer.VALUE});
                            dropDown.ID = answer.Q_ID.ToString(); //Since all Question IDS are the same, this should work just fine
                        }
                        dropDown.ClientIDMode = ClientIDMode.Static;
                        dropDown.Items.Insert(0, new ListItem { Text = "Select", Value = "" });
                        dropDown.Items.FindByText("Select").Selected = true;
                        
                        userControl.Controls.Add((Control) newControl);
                    }
                    else if (castedControl is RadioButtonList)
                    {
                        var radioButtonList = castedControl as RadioButtonList;
                        foreach (var answer in answers)
                        {
                            radioButtonList.Items.Add(new ListItem { Text = answer.ANSWER1, Value = answer.VALUE });
                            radioButtonList.ID = answer.Q_ID.ToString(); //Since all Question IDS are the same, this should work just fine
                        }
                        radioButtonList.ClientIDMode = ClientIDMode.Static;
                        userControl.Controls.Add((Control)newControl);
                    }
                }
            }
        }