basic genetics

[Bert Gold]

The simple answer to the question is that women have a nondisjunctive
predisposition at advanced maternal age, while men do not show this
predisposition until much later (and to much less an extent).

But perhaps you should just consult a good human genetics text
like Thompson and Thompson or Curt Stern's old book instead
of making a world-wide appeal for standard information.

I would imagine (though I haven't checked) that if you read
the Encyclopedia Britannica entry for Downs Syndrome you
would find an adquate explanation.

Discover a library; it is a worthwhile place.

Bert Gold, Ph.D.
University of California, San Francisco
School of Medicine
(In the Library)