How Am I Related to my Mother? Adapted from: EPID Ashley Larry Samia

We often have a sense that we are related to our mother in some way… “A chip off the old block!” “Like mother, like daughter.” “She’s got her mother’s eyes.” Appearance Abilities and talents Similar behavior and personality High blood pressure runs in the family… “Sharing the same blood”

Learning Objectives Photo courtesy of Understand that half of our genes come from our mothers. Understand why we are not exactly like mom – or even half of her. Learn what genetic testing can and can’t tell you about your relationship with your mom.

The Passing of Genes: key concepts The passing of genes from parent to child is the basis of inheritance. Traits are physical or behavioral characteristics such as height, eye color, hair texture, personality, talents, skills, inheritance of diseases. We receive traits in the form of genes from our mother and father. Each individual has two complete sets of 23 chromosomes. Chromosomes are composed of DNA that contains two copies of genes for each of our traits. A child receives half of his or her chromosomes from mom and the other half from dad, thereby inheriting both the copies of genes for each trait.

In the Beginning… Most of us are familiar with the basics of human reproduction – the female egg (ovum) is fertilized by a male sperm… The egg and sperm that you came from each contained half of your chromosomes. The egg, from your mother, contained 23 chromosomes from one of her single cells (See meiosis) But you’re not exactly half of your mom because the DNA from each set of her chromosomes got mixed up in the process of making her egg (recombination). zygote Illustration courtesy of bin/bvisapi.dll/discover/discover_circle.jsp?cid= &pid=11458&id=27495&lang=en

How Many Combinations of Different Traits Can Parents Pass on to Their Children? The traits that you inherit from your parents depends upon the combination of chromosomes that you receive from each parent.

Oh, the possibilities! Illustrated below is just ONE possible combination of chromosomes that a child can inherit from your mother What mom might contribute: 1319X

But Wait! There’s More! You also inherit chromosomes from your father; here is ONE possibility What dad might contribute: From each parent, there are or about 8,388,608 – possible combinations of chromosomes! That’s why we don’t look exactly like our brother or sister… X

…Other mutations that you have at birth are due to random chance… Some of what you inherit from your mother are mutations… …You may already sense that your mother is a mutant… …Does this make you one too?…

Genetic testing may help you find out some information about the mutations you carry, and where they come from  But…You may need to know more about your father’s genetics too.  Even then, it may be impossible to trace a particular mutation to its source – your mother or your father or random chance

OK, but should you get a genetic test anyway? If you get a genetic test, is this something to share with your mother? What would this mean?…  These are very difficult, and personal questions, that require careful consideration and reflection for most of us.

What We’ve Learned We are genetically related to our mother because we inherit one copy of her chromosomes. The copy of our mom’s chromosomes that we inherit is not exactly “half of mom” because the genes get shuffled when her eggs are produced. Genetic testing can tell us something about our relationship with our mother, but not everything.