Pedigree Charts

Symbols

• Circle = female
• Square = male
• Normal or without

trait = unshaded

• Trait = shaded

Symbols

• If an individual

has one
recessive allele
for a trait, the
person is a
carrier. This is
shown with a
half-shaded
square or circle.

Symbols

• Married couple or

couple producing
offspring =
horizontal line
connecting
midpoint of circle
and square

Symbols

• One offspring

• Multiple Offspring

How do you
differentiate between
a brother and sister
and a husband and
wife on a pedigree?

Generations

• Each generation

is (often) labeled
with a Roman
numeral.

• Oldest generation

at top of pedigree

• Current

generation at
bottom

Generations

• Individuals in

each generation
may be
numbered or
named.

• Siblings are

placed in birth
order from left to
right.

1 2

1 2 3 4 5 6

1 2 3 4 5

Polydactyl Trait

• Based on the

pedigree chart, is
the trait for
multiple digits
(fingers and toes)
dominant or
recessive?

• How can you tell?

Analyzing a Trait

• Sometimes a

pedigree is
drawn without
the carriers
shown.