Doesn't the answer to this problem require some input from
biology.... i.e. in order to do the conventional counting you have to
assume that the outcomes are random and independent. For some species
(e.g. humans) twins, triplets, etc. are much more likely to be of the same
sex owing to the biology. There must be a dog breeder or two on the list
who can enlighten us about the reproductive biology involved here.
Dr. Mark H. Shapiro
Physics Department
California State University, Fullerton
P.O. Box 6866
Fullerton, California 92834-6866