Relax or disable table constraints when using Dapper and Entity Framework?

I would like to set a do something like this dataSet1.EnforceConstraints = false; using the Dapper.Net ORM and Entity Framework.

I created the models in VS2010 where a property:

    [EdmScalarPropertyAttribute(EntityKeyProperty=false, IsNullable=false)]
    [DataMemberAttribute()]
    public global::System.String ethnicname
    {
        get
        {
            return _ethnicname;
        }
        set
        {
            OnethnicnameChanging(value);
            ReportPropertyChanging("ethnicname");
            _ethnicname = StructuralObject.SetValidValue(value, false);
            ReportPropertyChanged("ethnicname");
            OnethnicnameChanged();
        }
    }

... when value is null, I get a constraint exception at StructuralObject.SetValidValue... . How and where do I turn this off?

My data call looks like this:

    public DAL.Models.PROFILE GetProfile(int profileID)
    {
        using (IDbConnection connection = OpenConnection("MyDBConnectionString"))
        {
            try
            {

                var profiles = connection.Query<DAL.Models.PROFILE>("SELECT * FROM PROFILES WHERE ID=@ID", new { ID = profileID }); // IEnumerable
                var profile = profiles.First<DAL.Models.PROFILE>();

                return profile;
            }
            catch (Exception ex)
            {
                ErrorLogging.Instance.Fatal(ex);
                return null;
            }
        }
    }