Every living cell has genes. Genes are like a built-in instruction book for the cell. Genes tell sells what to look like, how to act, and how to survive.
Genes group themselves together in a chain-like formation. We call this DNA. DNA is the abbreviation for deoxyribonucleic acid. Don’t worry—you can just call it DNA like everybody else does.
Everyone’s DNA is different—unless you are an identical twin. The DNA of a living thing joins to form chromosomes. Chromosomes always come in pairs and every living thing of the same kind has the same number of chromosomes. EXAMPLE:
Every human has 23 pairs of chromosomes. IF they don’t there are abnormalities such as mental or physical handicaps.
NOTE: If you are an identical twin your DNA is the same because two people were formed from one egg.
Where do my Genes come from
You get your genes from your parents. When the sperm from your father fertilized the egg from your mother, you received half of its chromosomes from each parent. The chromosomes you receive from each parent are planned by nature.
What your genes give you
Your genes decide what color your hair is, what color eyes you have if you will be bald when you are older (boys), the shape of your body, the color of your skin if you are a boy or a girl, and lots, lots more.
EXAMPLE: If the father gives an XY chromosome, the baby will be a boy. If he gives an XX chromosome, the baby will be a girl.
You also get genes from your grandparents
Your parents got their genes from their parents…who got their genes from their parents. So when you think about it, there’s a good chance you can have characteristics of many different family members.
What genes are dominant in your family
Genes are divided into 2 categories: Dominant and Recessive. Dominant genes are stronger than recessive ones.
Let’s take a closer look at the members of your family to see what genes are dominant—meaning which ones show up most often.
Here is what you need:
- Paper and pencil
- Pictures of you, your siblings, your parents, grandparents, aunts, uncles, and cousins
Here is what you do
- Separate the pictures into three main groups: You and your siblings, your father’s family, and your mother’s family
- Place the pictures from each group in a line from the oldest relative to the youngest
Using the pencil and paper record the following for each group of pictures:
- How many people are tall
- How many are short
- How many have dark hair
- How many have light hair
- How many have red hair
- How many have curly hair? Straight hair?
- How many men are bald?
- How many have blue eyes?
- How many have brown eyes?
- What is the dominant body type in each group? Thin? Heavy? Muscular?
- Which family members look alike?
- Who do you look like? Why?
Here is what happens:
Parents pass their genes onto their children, who pass them on to their children. That is why it is not unusual for you to look more like your grandma or our cousin than you do your siblings. Another reason you have the genes you have is your cultural heritage. EXAMPLE: Asian people have distinctive characteristics that Mexicans or people from Sweden do not have.
- What is your cultural heritage?
- What are the most common physical traits of people with your heritage?
- Do you have these traits?