Explain how one becomes left/right handed or even ambidextrous......

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trophyhunter1 eNotes educator| Certified Educator

Handedness is a genetic trait, which follows Mendelian genetics principles of inheritance. In this instance, right handedness is the dominant allele or gene  and left handedness, is the recessive allele, or gene. Therefore, there are three different genotypes a person can have. If we use the letter Capital R for right handed gene, and lower case r for left handed gene, then a person who is RR is a righty who is homozygous for this trait(both genes are for Right handedness). Another combination is Rr and this person is heterozygous for Right handedness(both genes are different). Although this person has a righty and a lefty gene, righty genes are dominant and are expressed and the lefty gene remains hidden.  The third combination a person may inherit are two lefty genes, or rr. In this example, the person is homozygous for left handedness. When two recessive genes are in a person's genetic makeup, this is the only way they will be expressed,  and that person is a lefty. Statistically, 75% of the population is right handed and only 25% is left handed. A person may be ambidextrous usually due to an injury, where they learn to use the other appendage, or they can learn to use their non-dominant hand. For example, if someone is left handed naturally, because so many appliances and devices are made for righty's, they can learn to use their right hand with practice. In sports, being ambidextrous is encouraged.