Genealogy and genetics go together. Your genes play a role in everything from the color of your eyes to the potential for you to pass certain health conditions onto your offspring. Genealogists of today can benefit from having a good understanding of genetics. Here are some basic facts about genes to help you brush up on your knowledge.
Genetics is the study of genes, heredity, and variation in living organisms. Genes are tiny things that a person inherits from his or her parents. Each gene plays a role in determining specific characteristics in a person. Chromosomes are long DNA molecules. Most humans have 23 pairs of chromosomes (for a total of 46 chromosomes) in each cell. One chromosome from each pair comes from a person’s biological father. The other chromosome in each pair comes from the person’s biological mother.
Twenty-two of the pairs of chromosomes look the same in both males and females. The twenty-third pair are the sex chromosomes. These are not the same in all people. Females will have two copies of the X chromosome. Males will have one X chromosome and one Y chromosome.
It is worth noting that it is possible for a person to be born with a different than typical amount of chromosomes. Klinefelter syndrome occurs in males who have XXY. Triple X syndrome occurs in females who have three X chromosomes. People who have Down Syndrome (or Trisomy 21) have all or part of a third copy of chromosome 21.
When people say that something “runs in the family” what they really are saying is that more than one person in the family has a specific physical trait or health related condition. Some disorders are caused by gene mutations that can be passed from parent to child. A genetics professional can use a person’s medical family history to determine whether a certain condition is an inherited one.
Polymorphisms are genetic changes that occur in more than 1 percent of the population. People look upon these mutations as “normal”. Polymorphisms could be the reason why a person has a certain eye color, hair color, or blood type. Most polymorphisms have no negative affects on a person’s health. Other, less common, mutations can influence the risk a person has of developing certain disorders.
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