Personal Genetic Profile
Examining inherited human characteristics of myself and family to see if they are
dominant or recessive phenotypes. The characteristics examined will be straight thumbs or
‘hitch-hiker’ thumbs, tongue roller or non-roller, free ear lobe or attached ear lobe, 2 cords or 3
cords in flexed wrist, and left thumb on top or right thumb when hands are clasped . Materials
– Mirror Procedures
1. Tongue rolling
Try to roll your tongue into a U shape, with the groove down the middle. Tongue rolling
is dominant to non-rolling.
2. Straight thumb vs hitch-hiker’s thumb
Try to bend your thumb back towards your body (without help from your other hand). A
thumb that curves back is called a hitch-hiker’s thumb. The gene for hitch-hiker’s thumb
is recessive to the gene for a straight thumb.
3. Flexed wrist
Clench your fist and flex your wrist. Can you see two or three cords? Two cords are
dominant to three cords.
4. Ear lobes
Examine your ear lobes. Free ear lobes are dominant to attached ear lobes.
5. Clasped hands
Clasp your hands in front of you. Is your left thumb over your right thumb? Left over
right is dominant over left. Observations
Alanna’s possible genotypes
Hand clasp Dominant/Recessive
TT or Tt
WW or Ww
CC or Cc Family’s Results from each procedure
Hand clasp Alanna
Straight thumb 2 cords
Left thumb 2 cords
Right thumb 2 cords
Right thumb 2 cords
Left Thumb Analysis
First, I looked at the tongue rolling phenotype, represented by T/t, and observed
everyone in my family, including myself, could roll their tongue. This means we could possibly all
have the homozygous dominant genotype, TT. It could also be possible my parents are each
heterozygous dominant, Tt. If this was the case, if they had 4 children ¼ would be homozygous
dominant, TT, 2/4 would be heterozygous dominant, Tt, and ¼ would be homozygous recessive,
t, meaning that offspring could not roll their tongue. The ratio would be 1:2:1. There is also the
chance one of my parents has the homozygous dominant genotype and the other one
heterozygous dominant, if these genotypes are put into a Punnet square, there is a 1:1 ratio of 2
offspring being homozygous dominant, and 2 heterozygous dominant.
When viewing my family’s thumbs, represented by H/h, everyone but my father had the
recessive phenotype for ‘hitch hiker’s’ thumb, he had the dominant straight thumb. My father
must have the heterozygous dominant genotype, Hh, and my mother, brother and I have the
homozygous recessive genotype, hh. When looking at a Punnet square, with my father’s
heterozygous dominant genotype, Hh, and my mother’s homozygous recessive genotype, hh,
there could have been a ¼ chance of an offspring with the heterozygous genotype, the same as my father. Knowing that at least one child with the recessive phenotype, means the father is
Observing my family’s flexed wrists, represented by W/w, everyone had 2 cords
showing. This means we could all be homozygous dominant, WW, or possibly heterozygous
dominant, Ww. If my parents were both heterozygous dominant, and are expecting a fourth
child, this child could still have a 75% chance of having 2 cords, and a 25% chance of 3 cords.
This is because chance has no memory. In a Punnet square, it is possible 1 offspring could have
been homozygous recessive, ww, 2 offspring heterozygous dominant, Ww, and one offspring
homozygous dominant. Another possibility being one parent is homozygous dominant, and the
other one heterozygous dominant. In a Punnet square this would show a 1:1 ratio of 2 offspring
being homozygous dominant and the other 2 offspring being heterozygous dominant.
Identifying my family’s ear lobes, represented by E/e, my mother and brother have
detached ear lobes, and my father and I have attached ear lobes. This means my mother and
brother must be heterozygous dominant, Ee, and my father and I are homozygous recessive, ee.
When my parents reproduced this showed a 1:1 ratio. If they had four children, 2 offspring
would have the heterozygous phenotype, detached earlobes, and the other two would have
attached ear lobes, the homozygous recessive phenotype.
Lastly looking at clasped hands, represented by C/c, I got the same results as the ear
lobes, but switched. My father and I got heterozygous dominant, Cc, and my brother and
mother got homozygous recessive, cc. This means my father and I put our left thumbs overtop,
and my mother and brother put their right thumbs overtop. If we put these results on a Punnet
square, 2/4 offspring would be heterozygous dominant, while the other 2/4 offspring would be
homozygous recessive, and the ratio would be 1:1.
In humans, the chromosomes come in pairs, called homologous pairs, they carry genes
for the same traits in the same order, Alternate forms of a gene for the same trait are called
alleles, always on the same spot on each member of homologous pair. Alleles are represented
using letter, for example T would represent the dominant genotype, while the t would represent
the recessive genotype, the hidden one. There can be three types of genotypes for single traits,
TT would be homozygous dominant, Tt would be heterozygous dominant and t would be
homozygous recessive. Environmental factors can also play a roll in the expression of traits.
Polygenic traits seem to be particularly influenced by the environment. The traits we looked at
were not influenced by the environment, because they are inherited and not influenced by
temperature or nutrition. Conclusion
After looking at all my traits, 3 out of 5 were dominant phenotypes. My father and I have
4 out of 5 of the same traits, and my brother and mother have all the same phenotypes. I did
not have any problems with looking at everyone’s phenotypes, and had no sources of error. Resources
– Mader, Sylvia. Inquiry into Life. 12th ed. Pgs 471 – 488 Science