private void Form1_Load(object sender, EventArgs e)
{
foreach (Control ctl in checkBox1.Parent.Controls)
{
if (ctl is CheckBox)
{
((CheckBox)ctl).CheckedChanged += checkedChanged;
}
}
}

private void checkedChanged(object sender, EventArgs e)
{
var chk = (CheckBox)sender;
foreach (Control ctl in chk.Parent.Controls)
{
if ((ctl != chk) && (ctl is CheckBox))
{
ctl.Enabled = (chk.Checked == false);
}
}
}