Have you ever wondered why you look so much like your parents? The answer lies within your DNA, the blueprint that defines your unique traits. But how much of this genetic material do you inherit from each of them?
Is it a 50/50 split? Or does one parent contribute more than the other? The implications of this question are far-reaching, from understanding genetic diseases to tracing family lineages.
Below, we explore the nuances of DNA inheritance to help you understand how the interplay of genetics makes you, well…you.
» Discover how much DNA you share with your parents using a DNA kit
Types of DNA inherited from parents
Autosomal DNA
Autosomal DNA is the 22 pairs of chromosomes that aren’t related to gender (X and Y). We get one chromosome from each parent in each pair. These chromosomes have “genes” on them, which are like blueprints for our traits.
When our parents’ cells divide to make sperm or eggs, their genes can mix and match. This means that even though we get half our DNA from each parent, our DNA is unique, just like our fingerprints. It’s different from our parents and even our siblings.
» Understand the structure of DNA
Sex chromosome DNA
Sex chromosomes are the pair of chromosomes that determine whether a person is male or female. Usually, women have two X chromosomes. On the other hand, men have one X chromosome (from their mothers), and one Y chromosome which they inherit from their fathers.
Sometimes, people are born with different combinations of sex chromosomes. For example, people with Klinefelter syndrome have three sex chromosomes (XXY), and people with Turner syndrome have only one sex chromosome (XO). These are called intersex conditions.
» Learn how to use chromosome browsers for genealogy
Mitochondrial DNA (mtDNA)
Mitochondria, often called the “powerhouses of the cell,” are essential for our existence. They produce adenosine triphosphate (ATP), which our cells use for energy. Mitochondria are found in all living things on Earth. They evolved independently and were absorbed by other cells over 1.45 billion years ago. [1]
We inherit mtDNA almost exclusively from our mothers. In reproduction, mitochondrial DNA comes only from the egg. We can use this fact to trace our maternal lineage back through generations. All of our great-grandmothers, their daughters, and their daughters’ daughters will have nearly identical mitochondrial DNA.
» Discover the importance of an mtDNA test
Mutations and variations in genetic inheritance
Mutations happen when there is a change in the DNA sequence in a cell. They can start in any cell, but only mutations that occur in sperm or egg cells can be passed down to offspring. [2]
Mitochondrial DNA mutations can cause neurodegenerative disorders and muscle wasting. [3,4] These mutations are only passed down from mothers to their children, affecting both sons and daughters, but only daughters can pass them on.
On the other hand, genes can be passed down in different ways from a parent to a child:
- Recessive: You need to get the same gene from both parents to have the trait. [5]
- Dominant: You only need to get the gene from one parent to have the trait.
- X-linked: These genes are on the X chromosome. Boys are more likely to have these traits if they get the mutated gene from their mother. [6]
» Find out more by maternal and paternal lines
How DNA testing helps you find relatives
DNA testing works by cutting DNA into smaller pieces, sorting them, and staining them. The patterns help identify the pieces based on their location on the chromosomes. This confirms the 22 pairs of chromosomes from each parent and the sex chromosomes.
MyHeritage shows DNA matches with information to help you figure out relationships. This includes the shared DNA percentage, an estimated relationship, the number of shared segments, and the size of the largest shared segment. It also shows information your matches have added, like their age, surnames, and places from their family trees.
FInding relatives through DNA
Shared DNA percentages only provide part of the answer you need to build a family tree. A percentage corresponds with at least one likely kinship and sometimes with several possible relationships. Even a 50% match could be a parent, a child, or the identical twin of either your parent or your child.
Knowing the ages of the subjects whose DNA is being compared can help narrow that down. Still, other possible relationships cannot be clarified without gathering more information than a shared percentage of DNA.
Someone who is a 6.25% match for your DNA might be a half-first cousin, a half-great aunt or uncle, a double-second cousin, a twice-great grandparent or grandchild, or a double-first cousin twice removed, and this is not an exhaustive list.
A DNA Blueprint to Learn Your Genetic Secrets
As we’ve learned, the question of how much DNA you share with your parents is more complex than it might seem. While we inherit about half of our genes from each parent, the specific genes and variations can differ greatly. This is because DNA is shuffled during sperm and egg formation.
Understanding how DNA is inherited helps us appreciate each person’s uniqueness. It also has important implications for fields like genetics, medicine, and family history. By studying our DNA, we can gain valuable insights into our health, ancestry, and life experiences.
» Wondering how much DNA you share with your parents? Try a DNA kit
