Finding ID of the check box control in child grid

public static T FindControl<T>(this Control parent, string controlName) where T: Control
    {     T found = parent.FindControl(controlName) as T;
    if (found != null)
    return found;
    foreach(Control childControl in parent.Controls)
{
    found = childControl.FindControl<T>(controlName) as T;
    if (found != null)
    break;
}
return found;
}