Pedigree Activity- Dimples
In this lab you will be following a story of a family that is very proud of their dimples. You will be constructing a
pedigree chart for several generations of this family. Having dimples is a dominant trait and not having dimples is a
recessive trait. A person that has this trait must have inherited at least one dominant gene (D) from one of
his/her parents. Therefore, the genotypes for people with dimples could be “DD” or “Dd”. A person without dimples
would have both recessive alleles and their genotype would be “dd”. Remember that a person gets one gene for this
trait from each parent. A parent with the genotype “dd” can give only the recessive gene to his/her offspring.
Rules for making a pedigree chart: USE PENCIL!!!!!
1. Males are represented as squares and females as circles.
2. Children are listed in order of birth. (When reading this story, assume the order of birth is the order that the
story is read in.)
3. Below each circle or square, list the name and then below the name list the genotype.
4. Remember to shade in your squares/circles for people who show the trait or half shade for those who are
carriers for the trait but don’t show it.
Construct a pedigree chart for the following story and then answer the questions that follow.
Grandfather and Grandmother Smith smiled a lot and showed off their dimples
each time. They had a son named John, who had dimples, and daughter named
Julie, who did not. Julie died at an early age, but her brother John Smith met and
married Mary Jones because she had the most beautiful dimples when she smiled.
They had 5 children, 2 boys and 3 girls. Only one of their sons, Tom, had dimples,
but both girls, Judy and Kay, had dimpled smiles. Their sister June lacked dimples.
After college, Tom met and married Jane Kennedy who also had dimples. They had
3 children, all girls, who shared their parent’s dimpled smile. Tom’s sister Kay
married a lawyer named James who seldom smiled and didn’t have dimples. Their
only son Matthew was like his mother when he smiled. Judy never married. Tom’s
sister, June, married a doctor and had 5 children. Three of the children were
boys, Jay, Fred, and Mike. Mike and Fred had dimples like dad, but Jay’s smile was
like his mom’s lacking dimples. One sister, Susan, had dimples, but the other,
Katherine, didn’t.
Questions- You can answer these questions on the back of your pedigree chart.
1. What type of information does a pedigree contain?
2. How do you show the presence of a trait in a pedigree?
3. How do you denote males & females in a pedigree?
4. From your pedigree, is the presence of dimples a dominant or recessive trait?
5. How could examining a family pedigree be helpful to a couple wanting to have children?