Right or Left-handed?

Scientist hypothesizes that between 70-95% of Earth's population are right-handed, and the remaining 5-30% are left-handed. Only a couple of percent have an equal strength in both arms.
Scientists are positive that inheritance has a huge part, weather the offspring would be right or left armed. AS noticed right armed is dominant, while being left-handed is recessive. Thus, it would require two left-handed genes (alleles), one from each parent, for the offspring to become left-handed. However if there was to appear that one or both genes (Alleles) were right-handed-alleles, the offspring would appear right-handed.
Here is a table, which shows the ratio of having a offspring which is right or left-handed:

R = Right-handed gene/allele (Dominant)
L = Left-handed gene/allele (Recessive)

As probably noticed, the ratio of being right-handed to left-handed is 3:1
3+1 = 4
Thus, thus probability of having a right-handed offspring would b ¾, thereby 75% (4/3 =0,75 0,75*100=75%). Because it requires two genes for the offspring to become left-handed, the probably for getting a left-handed child I much less. 4/4 - ¾ = ¼. Hence, the probability for getting a left-handed child is ¼ or 25% [100% - 75%]

Using a punnet square we notorious humans, can calculate the ratio and probability for what hand the offspring would have most strength in, however for that, we need to know the alleles for both parents.

For instance if Sam [A made up Character] has a genotype r| r[the alleles] [Phenotype - left-handed], and marries Madeline [another made up Character] who is right-handed.

Sam

If Madeleine is homozygous (Alleles [R | R])

This punnet square shows us that If Madeline is homozygous, their offspring is defiantly going to be right-handed
Ratio - 4:0

Sam

If Madeline is Heterozygous

Here we can observe that if Madeline is heterozygous, the ratio of the offspring becoming right-handed would be 2:2

Here we can observe that if Madeline is heterozygous, the ratio of the offspring becoming right-handed would be 2:2

Therefore calculating a offspring's characteristics for thing such as hair color, skin color , which hand he/she would prefer to use, isn't very hard using a punnet square, however for us to know this, the r3equirement is the knowledge of both parents alleles.

Concluding, I would like to add, that there are certain other considerations weather a person is a typical/real right-handed of left-handed or not. With this, I mean that, there are certain social reasons, which can affect the offspring. For instance, in certain societies being left-handed is not very appreciated, and those people are often bullied or considering having brain faults, thus in some societies, the students are forced to use their right hand, even though they prefer to use their left-hand. They are some times also considered being abnormal. The Latin word for left-handed, "Sinister" also means abnormal. Because of these reasons, some "typical" left-handed people consider/claim themselves being right-handed, in public, and that affects the statistics.

Sources:
Illustrerad Vetenskap Nr 10
Classroom notes
Oxford Advance learners Dictionary

Glossary -

Homozygous - A person who's two alleles are identical. E.g. [ R | R ]
Heterozygous - A person who's two alleles are different. E.g. [ R | r ]
Genotype - What alleles an organism has.
Phenotypes - A physical description/characteristics, such as brown hair, right-armed, etc.

Written By:

VIRPAL SINGH 9C