This slideshow was created to show why determining paternity via physical traits is far from accurate and a dna paternity test is preferred.

1. Determining Patern
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2. Introduction
 Basic Genetics
 Homozygous and Heterozygous
 Dominant or Recessive Traits
 Examples of Simple Inheritance of
Traits that Show Complete
Dominance
 Using Simple Inheritance to
Determine Paternity
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3. Basic Genetics
Few human traits are based on
simple inheritance where one
version of a gene (dominant allele)
masks the expression of the other
version of that gene (recessive
allele). This article will discuss
these traits and understanding
their importance in determining
paternity.
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4. Homozygous and
Heterozygous
 How it relates to your aA gene with identical
alleles for a single trait is said to be homozygous,
and having different alleles is said to be
heterozygous. For example, the gene for widows
peak exists in two forms, one form or allele
results in a V-shaped front hairline (W) and the
other for straight front hair line(w).
 A homozygous individual would contain the
following alleles: (WW) or (ww). A heterozygous
individual would contain the following alleles:
(Ww).
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5. Dominant or Recessive
Traits
 In cases of simple inheritance, where a characteristic is controlled by
one pair of alleles and one allele is dominant over the other, this is
called complete dominance. For that characteristic, an organism will
have one of two phenotypes.
 Using the previous example, an individual with a recessive phenotype
(straight hairline) possesses a genotype consisting of two recessive
alleles (ww).
 An individual with the dominant phenotype (widow's peak) can be
either homozygous(WW) or heterozygous (Ww). It is more difficult to
know genotype when dominant allele is involved.
 If both parents exhibit the dominant trait, their offspring have a
50-100% chance of inheriting the dominant trait. If only one parent has
the dominant trait, there is a 50% chance that their offspring will have
the dominant trait. If neither parent exhibits the dominant trait, there is
no chance their children will have the dominant trait.
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6. Examples
 Cleft Chin
 A prominent cleft in the chin is due to the
bond structure which underlies the Y-
shaped fissure of the chin. A cleft chin is
the dominant phenotype due to the
presence of the cleft gene. Females
appear to be less conspicuously affected
than males.
 EXCEPTION: Scientists now say there
are two genes involved in this phenotype.
Thereby making it possible for two cleft
chin parents to have a child without a
cleft chin
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7. Blue Eye Color
 The blue eye color allele is recessive. This
means that both genes must have both blue
alleles i.e. "blue-blue", in a person with blue
eyes. Parents with non-blue eyes can have
offspring with blue eyes. However, two blue eyed
parents have only blue eyed children.
 EXCEPTION: There are cases of blue eyed
parents having brown eyed children. One of the
parents may be secretly be carrying a slightly
mutated allele for brown eyes. Although the
mutated brown eyed allele is silent in the parent,
the child inherits the non-mutated version.
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8. Dimples
 A dimple is the outcome of a fault in the
subcutaneous connective tissue that
develops during embryonic development.
Since the dimple gene is dominant, a
child has dimples if the gene is present
in him/her.
 EXCEPTION: The dimple gene is
dominant; however, it is not always
expressed.
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9. Earlobes
 The dominant trait is for lobes to hang
free, a bit of lobe hanging down prior to
the point where the bottom of the ear
attaches to the head. With the recessive
phenotype, the lobes are attached
directly to the head.
 EXCEPTION: There are cases of people
having one attached earlobe and one
free-hanging. These cases show that
free-hanging lobes aren't always
expressed and earlobes can not be used
to determine paternity.
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10. Conclusion
Typically, maternity is easy to determine.
Unfortunately, there is no easy way to determine
paternity. The obvious first method is to compare
general physical appearance. Often inconclusive,
the next method is to read about Mendelian
genetics concerning simple inheritance, such as
this article. It is extremely important to note that
there are documented exceptions to every trait
listed above. For example, it is possible for a
particular gene to not be expressed and thereby
not exhibit traits associated with it. This is the
reason a DNA paternity Test should be the only
method to determine paternity when doubt is
present.
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