Title: Pedigree Analysis: A Family Tree of Traits
Overview:
Some characteristics, like the shape of your hairline, whether your earlobes are attached or
detached, and whether or not you have freckles, are inherited from your parents. In this
science project you'll see how writing these characteristics onto a family tree can help you
determine how they are inherited.
Content Standard(s):
Biology
7) Apply Mendel’s Law to determine phenotypic and genotypic probabilities of offspring.
a. Interpreting inheritance patterns shown in graphs and charts
Technology Education (9-12):
16) Create a product that integrates information from multiple software applications.
Shelby County Technology Skills:
Use Word to create organizational chart
Total Duration:
1 or 2 class periods
Materials and Equipment:
Computer with word processing software and printer
Procedures/Activities:
Just like Mendel observed generations of related pea plants to determine the mode of
inheritance for flower color and other physical traits, scientists can examine generations
within a family and discover the mode of inheritance for human traits. To do this, scientists
create family trees, called pedigrees, showing as many generations of a family as they can and
marking who had which phenotype. In order for scientists to understand each other's
pedigrees, they use a standard set of symbols and notations. For example, males are always
designated by a square and females are always designated by a circle.
In this science project, you'll create pedigrees for four human physical traits to determine
which phenotypes are dominant and which are recessive. All four are Mendelian traits:
 Do you have freckles or not?
 When you interlace your fingers, which thumb is on top—the right or the left?
 Do you have attached earlobes or detached earlobes?
 Some people's hairlines come to a V-shaped point above their forehead. This is called a
widow's peak. Do you have one or not?
To start this project, you should create a pedigree in Word showing the different members of
your family.
 Include as many family members as you can get data from. The more people and
generations you include, the more likely it is that you'll have enough information to
determine the mode of inheritance.
 You might need help from your parents to figure out all the relationships.
 Make four copies of the pedigree—one for each trait you are going to evaluate.
 Determine the phenotype of each person on your pedigree for each of the four
traits. Use a separate pedigree for each trait. Note: Widow's peak can vary
considerably; score any sort of V-shaped hairline as positive.
 From your pedigrees, can you deduce the mode of inheritance for each trait? For
which traits is your pedigree informative? If you don't have enough information to
determine the mode of inheritance of a particular trait, try making a pedigree for
another family.