try this
protected void Gender_SelectedIndexChanged(object sender, EventArgs e)
{
RadioButtonList rdb= (RadioButtonList )sender;
GridViewRow grdRow = (GridViewRow)rdb.NamingContainer;
GridViewRow grdRow = ((GridViewRow)rdb.Parent.Parent);
Label objLabel = (Label)grdRow.FindControl("ControlIDfromgridview");
String str= grdRow.Cells[0].Text;
}