I. IntroductionGregor Mendel initially studied transmission genetics using garden peas (Pisum

sativum). Humans, though, are a more complex organism vis-a-vis peas and require a much more intricate procedure than the simple crosses by Mendel. Special methods must, thus, be utilized to analyze inheritance pattern in humans. The family pedigree, a modification of the family tree, is a standard method of genetic analysis in humans. The objective of this exercise is to use a family pedigree to extrapolate the possible mode of inheritance (i.e. heterozygous or homozygous) of an individual for a certain trait based on the presence and/or absence of the same trait in proximal relatives (e.g. siblings and cousins). Additionally, it aims to calculate the probabilities of a theoretical offspring between 2 assumed parents in the class of having each of 16 individual traits and multiple traits (e.g. 2, 3, 4, and 5) at the same time.

II. Materials and MethodsEight individual family pedigrees were constructed for each of eight particular

traits, namely: ear lobe attachment, tongue-rolling, handedness, hair smoothness, hairline shape, cleft chin presence, eyebrow shape and dimple presence. The phenotypes of immediate family members were observed. Based on the phenotypes of each individual in the pedigree, the possible genotypes (i.e. heterozygous, homozygous dominant or homozygous recessive) were subsequently determined.

Then, a marriage was assumed between two individuals in class and the probabilities were calculated for a theoretical offspring inheriting 16 individual traits from the two assumed parents. The probabilities of that offspring having 2, 3, 4 and 5 of these traits, at the same time, were also calculated. The forked-line method was utilized to derive these probabilities.

III. Results and DiscussionsThe genotypes of each individual in the pedigree were determined using the

observed phenotypes. Each of the eight pedigrees for the eight traits showed unique modes of inheritance. This speaks volumes of the Law of Independent Assortment. This law says that different traits are inherited independently of each other. This means, for example, that the inheritance of hair smoothness will not affect the inheritance of hairline shape. The phenotype, and hence the genotype of individuals in a certain generation will, most of the time, not be the same across the board. Although, when the inheritance of a trait is consistent among siblings from their parents, it is most likely that the parents, and consequently the offspring are homozygous for that trait. Meanwhile, if the phenotype is not consistent throughout the sibship line or if the parents both possess a certain trait but an offspring possesses the opposite trait, there is a high probability that the parents are heterozygous for that trait. To make sure even more of what genotype to assign for each individual in a generation, one should consider going back one more generation, where the grandparents are. The pedigree analysis can not only extrapolate the mode of inheritance of an individual for a certain trait, but it can also trace from which ancestor a certain disease come from.

It is important to note, though, that majority of the traits analyzed were Mendelian, meaning that there is a clear dominance/recessivity between the two possible alleles for a trait. However, the handedness trait, upon the analysis of the pedigree and some further research was discovered to be a non-Mendelian trait. Out of all the individuals in the pedigrees, which covers three generations, only one, me, is left-handed. Handedness has a special inheritance pattern. When both parents are right-handed, there is only a one out of ten chance that an offspring might be left-handed. If both parents are left-handed, there is only a four out of ten chance that an offspring might be left-handed. This speaks volumes of the concepts that go beyond Mendelian genetics, which explores the more intricate traits that are passed on from generation to generation.

Meanwhile, the probabilities of trait inheritance of the hypothetical offspring yielded varying ratios across the board, especially when it comes to multiple inheritance. This, again, speaks volumes of the Law of Independent Assortment. Although, some ratios exhibited common iterating patterns, as would be expected for Mendelian traits.

IV. ConclusionThrough the creation and subsequent analysis of the family pedigree and the

inheritance probability calculation of traits in a theoretical offspring, the postulates of Gregor Mendel were accentuated. Being that the traits analyzed were Mendelian, dominance/recessivity was demonstrated by the traits. The individual traits are inherited independently of each other as evidenced by the varying modes of inheritance in each of the pedigrees per trait and the different ratios of inheritance probability per trait for the theoretical offspring. Some non-Mendelian trait were also explored and discovered to have much more complex modes of inheritance vis-à-vis Mendelian traits.

V. List of ReferencesKlug WS, Cummings MR, Spencer CA, Palladino MA 2014. Essentials of

Genetics. Pearson New International Edition. Harlow, Essex, England: Pearson Education. pp. 61-62

Weber B. Being left-handed is not 'in the genes,' study shows. Medical News Today [Internet]. 2013 Oct 7 [cited 2016 Feb 29]. Available from: http://www.medicalnewstoday.com/articles/267047.php