Human Genetics Problem Set

Problem 10: Predicting inheritance pattern from pedigree analysis

A man who had purple ears came to the attention of a human geneticist. The human geneticist did a pedigree analysis and made the following observations:

In this family, purple ears proved to be an inherited trait due to a single genetic locus. The man's mother and one sister also had purple ears, but his father, his brother, and two other sisters had normal ears. The man and his normal-eared wife had seven children, including four boys and three girls. Two girls and two boys had purple ears. The purple-ear trait is most probably:

A. autosomal, dominant

B. autosomal, recessive

C. sex-linked, dominant

D. sex-linked, recessive

E. cannot be determined from this information

The Biology Project
University of Arizona
Revised: November 5, 1998
Contact the Development Team