public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            var lst = new List<x>(
                new[]
                    {
                        new x() {Id = 1, yy = new List<y>(new[] {new y() {y1 = "11", y2 = "12"},})},
                        new x() {Id = 2, yy = new List<y>(new[] {new y() {y1 = "21", y2 = "22"},})},
                        new x() {Id = 3, yy = new List<y>(new[] {new y() {y1 = "31", y2 = "32"},})}
                    });

            var view = lst.SelectMany(i => i.yy.Select(ii => new z() {Id = i.Id, y1 = ii.y1, y2 = ii.y2})).ToList();
            dataGridView1.DataSource = new BindingList<z>(view);
        }
    }

    public class z
    {
        public int Id { get; set; }
        public string y1 { get; set; }
        public string y2 { get; set; }
    }

    public class x
    {
        public int Id { get; set; }
        public List<y> yy { get; set; }
    }

    public class y
    {
        public string y1 { get; set; }
        public string y2 { get; set; }
    }

gridView.Rows.Add();
gridView.Rows[gridView.Rows.Count - 1].Cells[0].Style.BackColor = System.Drawing.Color.FromArgb(235, 235, 235);
gridView.Rows[gridView.Rows.Count - 1].Cells[1].Style.BackColor = System.Drawing.Color.FromArgb(235, 235, 235);
gridView.Rows[gridView.Rows.Count - 1].Cells[2].Style.BackColor = System.Drawing.Color.FromArgb(235, 235, 235);

gridView.Rows[gridView.Rows.Count - 1].Cells[0].Value = false;
gridView.Rows[gridView.Rows.Count - 1].Cells[1].Value = reader["aaa"].ToString();
gridView.Rows[gridView.Rows.Count - 1].Cells[2].Value = reader["bbb"].ToString();
int temp = 0;
for (int i = 0; i < list.Count; i++)
{
gridView.Rows[gridView.Rows.Count - 1].Cells[3 + i].ReadOnly = (reader["xxx_" + list[i].ToString()] == DBNull.Value);
[color=red]gridView.Rows[gridView.Rows.Count - 1].Cells[3 + i].Style.Alignment = System.Windows.Forms.DataGridViewContentAlignment.MiddleRight;[/color]
if (!gridView.Rows[gridView.Rows.Count - 1].Cells[3 + i].ReadOnly)
{
gridView.Rows[gridView.Rows.Count - 1].Cells[3 + i].Value = reader["zzz_" + list[i].ToString()].ToString();
}
}