One of the first thoughts that arise from a mother or father after the birth of a baby are: who does the baby look like? Are the baby’s features a combination of the mother and father or does he or she look more like one over the other? It’s fascinating to look at a family with multiple children and see the similarities and differences of a variety of features – physical, emotional, and even social. For me, I know that my body type was inherited from my father and my hair came from my mother. My siblings and I all look very similar, a combination of both of my parents. When it comes to genetic conditions and health concerns, I hear many people in a genetic counseling session say things like, “well, I’m more like my mom so I probably have it” or “I look more like my dad, so I probably didn’t inherit the gene.” Does that actually mean anything though?
To review, our bodies are made up of billions of cells. Inside each of these cells are our genetic instructions (DNA). Segments of DNA are called genes, which tell our bodies what to do – for example, how our muscles function, or how our heart pumps. All of these genes are packaged into chromosomes. We have 23 pairs of chromosomes, 22 pairs of autosomes and 1 pair of sex chromosomes that determine our physical gender. The reason for the pairs of chromosomes is because in each pair we get one from our mom and one from our dad. So, when looking at the number of chromosomes, we actually get an equal number of genes from our mom and dad.
However, there is one piece missing that I haven’t mentioned yet. In addition to chromosomes, we inherited something called mitochondrial DNA. Mitochondria are little organelles in our body that are the “powerhouse” of the cell. Basically, they provide the energy needed for our cells to function in our bodies. Mitochondria have their own DNA. And we inherit that DNA from our mother. When you add up all the genes in our body, we actually get more genes from our mother than our father. But what does “stronger” actually mean? Are we talking about quantity or influence over our bodies?
While we are still trying to figure this out, there are some thoughts regarding this topic. There are genes that we inherit from our mother and father that are called “imprinted genes”. Basically, what this means is depending on the imprinted gene (we have about 100-200 of these in our bodies) either the mother’s or the father’s imprinted gene that you inherited will be turned off, so that the other one is the only one working. This is different from the rest of our genes, where both copies of the gene are turned on. Based on the imprinted genes that we know about, we think that the number of father’s imprinted genes turned off and the number of mother’s imprinted genes turned off is about the same. However, we are still learning everyday about the human genome and will continue to discover more. There’s some early evidence in mice studies that possibly the father’s imprinted genes are turned on more than the mother’s, but only more research will tell.
One of the very unique set of genes that only a father can pass on is the Y chromosome – which makes a fetus a male. Females have two X chromosomes that make up the sex chromosomes, whereas males have one X chromosome and one Y chromosome. The Y chromosome is a smaller chromosome than the X chromosome and has about 70 – 200 genes. The main genes that we know about on the Y chromosome are sex determining genes. Ultimately, we don’t think it has additional roles in the body, but there is still a lot of research to be done.
Who has stronger genes – mom or dad? The most reasonable answer is they play equal roles. When it comes to inheriting a particular trait or gene mutation, it’s random. There isn’t a greater chance of you inheriting something from your mom compared to your dad. If you have a family history of a genetic condition or health concern and would like to speak to a genetic counselor, please contact AT-GC to schedule an appointment.