GG: descendent?

["Junichi Miyazawa" <walkingtune@bigfoot.com>]

Dear fm's,

My Japanese translation of GG Letters is almost finished.
I am polishing the text checking unclear words and phrases.

Here is a question in Gould's letter dated 10 September 1972
to Peter Symcox (producer at CBC Montreal), in which
GG wrote a plan of a program on Schoenberg.

English edition, p. 187, lines 15-21:

>> . . . we could also include some or all the six miniatures,
>> opus 19 [of Schoenberg].  In fact, this might not be
>> a bad idea, in any case, since, although like Pierrot
>> Lunaire and, as a deterined anti Stravinskian, I would have
>> to add, "Le Sacre," opu 19 is certainly one of the
>> linch-pins of history--works more important for the
>> results they engendered (op.19, I think,
>> a direct descendent of the Boulezian experiments with
>>          ^^^^^^^^^^^^^^^
>> timbre, etc.) than for any intrinsic merit they possess.

==

To me, "descendent" sounds odd.  Opus 19 (Six Piano Pieces)
was composed in 1911.  Boulez was born in 1925.  
The "experiments with timbre, etc." by Boulez are definitely
done after Opus 19.  This seems chronologically incorrect.
Does the word mean "ascendent" here?  
Was it a mistake by GG or was there any intention of his?


Let me have your ideas.

Thank you in advance.

Junichi