'----- start of code -----
    Dim strSourceTable As String

    With Forms!frmPeople

        strSourceTable =
            .Recordset.Fields(.Controls("txtFirstName").ControlSource).SourceTable
        Debug.Print "Source table for txtFirstName is '" & strSourceTable & "'"

        strSourceTable =
            .Recordset.Fields(.Controls("txtGenderDesc").ControlSource).SourceTable
        Debug.Print "Source table for txtGenderDesc is '" & strSourceTable & "'"

    End With
'----- end of code -----