How to handle Left joins

[Mech0z]

                var sql = @"select  p.*,

                                    a.""Id"" as ""Analysis_Id"",
                                    a.""Name"" as ""Analysis_Name"",
                                    a.""SortOrder"" as ""Analysis_SortOrder""

                                    from ""Product"" p

                                    left join ""Analysis"" a on p.""AnalysisId"" = a.""Id""

                                    where p.""CategoryId"" = :CategoryId";

                IEnumerable<dynamic> dynamicProducts = await
                        sqlConnection.QueryAsync<dynamic>(
                            sql,
                            new
                            {
                                CategoryId = categoryId
                            });

                var products = AutoMapper.MapDynamic<Product>(dynamicProducts).ToList();
                return products;

    public class Product
    {
        public long Id { get; set; }
        public long OFId { get; set; }

        public string Header { get; set; }
        public string Description { get; set; }

        public int CategoryId { get; set; }
        public Analysis Analysis { get; set; }
        public bool IsActive { get; set; }
    }

If AnalysisId is null, then Slapper.Automapper creates a new object with default values. How am I supposed to make it set Analysis to null instead of a "nulled" object?