April 9, 1970

Mrs. Jules Lederer
1000 Bake Shore Plaza
Chicago, Illinois 60611

Dear Eppie:

The question you mention in your letter about the possibilities of having
children blacker than either parent has come up again and again in my own
teaching career. If there is a resurgence of interest in it I hope it is
based on constructive curiosity, following upon recent relaxations of tabus
about interracial marriage - that may be too optimistic!

Let me try to fill you in, although I really would prefer not to have any
direct attribution since that may convey an undue sense of authority about

my answer, or any anewer that could be quoted in a few words. It is one of
those situations where a little knowledge might do very considerable mischief.
Were I to be asked about the expectations 6fom the kind of mating you describe,
I think I could very reasonably reassure a couple that thetr children would
"almost certainly” be no darker than the darker parent. On the other hand,
this is an area where our rigorous scientific information is much thinner than
you probably imagine, and ahdére is plenty of room for new discovery. It would
be exceptional for the child to be darker than I have indicated, but I cer-
tainly do not believe it would be real grounds for suspecting his paternity.
Pigmentation is the last character in the world that wne could rely upon for
making any crucial genetic judgments. There are many other factors, for
example the blood groups, which would be much more reliable.

To give a possibly extreme example of an exception to the usual rule, it
would be predicted that the mating of a Caucasian with a Negro who happened
to be carrying the mutant factor for albino would certainly result in darker
offspring. The generally accepted rule is, however, that children will have
a level of pigmentation roughly intermediate between that of their parents.

I am enclosing a couple of pagge from Curt Stern's textbook that you cer-
tainly could use as an authority for anything you wish to say about the subject.

Sincerely yours,

Joshua Lederberg
Professor of Genetics

\.4y¥4d57