My Family Pedigree – Pinky (straight vs. bent)
Bb
bb
1
2
Because having bent pinky fingers (B) is
a dominant trait and straight pinky
fingers (b) is a recessive trait. If you do
not have the trait, you MUST have the
genotype bb. All unaffected males and
females have the bb genotype.
I
bb
Bb
Bb
bb
II
1
2
3
Bb
4
The level III offspring are the result of
level II pairing of affected male 3 and
unaffected female 4. This pairing will
result in affected offspring with
genotype Bb and unaffected offspring
genotype bb.
bb
III
1
In level II of the pedigree, one of the
offspring is unaffected. This indicates
that the male in level I MUST have the
genotype Bb, so that at least 1 offspring
has the chance of being unaffected. This
will also determine the genotype of all
the level II offspring that are affected as
Bb.
2
Affected male
Unaffected male
Affected female
Unaffected female
NOTE: This pedigree is an example of a dominant trait in this family.