I to be a mommy of 2 boys, 3 years and 8 months. My husband has actually dark brown hair and brown eyes and I have light brown hair and blue eyes and also both ours boys have actually red hair. We can trace red hair ago two generations, however it skipped ours parents and also us. How does this happen?
-A curious adult native Arkansas
December 19, 2007
Traits prefer red hair or blue eyes that skip generations have the right to be frustrating (especially if your mailman has actually red hair and/or blue eyes!). But it is perfectly natural. And explainable by chrischona2015.org.
You are watching: How can a trait skip a generation?
Many of our traits come from ours genes. There room genes that identify eye shape, hair texture, hair, eye, and also skin color, etc. The properties that are most likely to skip generations are the ones caused by recessive gene versions. To recognize what this means, we have to remember two things around our genes.
First, we have two duplicates of most of our genes -- one native mom and also one from dad. And also second, ours genes have the right to come in different versions called alleles. These different versions can lead to different traits.
For example, there room versions the the MC1R gene that result in red hair. And versions that don"t lead to red hair.
What this all method is that people can have actually three feasible combinations that the MC1R gene. They have the right to have 2 non-red versions, 2 red versions, or one of each.
It is pretty evident that having two non-red versions means you won"t have red hair. And also that having actually two red versions method you will have red hair. But what if you have one version of each?
This is wherein recessive comes in. Not all version of genes are created equal -- some versions space "weaker" than various other ones. In chrischona2015.org speak, we"d say that some alleles are recessive and some are dominant. The red hair versions of the MC1R gene are recessive come the other MC1R versions.
So if you have actually a red and also a non-red variation of the MC1R gene, climate you won"t have red hair. Yet you lug the recessive red hair version that you can pass under to your kids. Another method to to speak this is that you are a carrier because that red hair.
Carriers space the reason why traits can skip generations. I am walking to use your story as a way of explaining why this is. I"ll additionally use the figure listed below to present what ns am saying in photo form.
Writing and also saying non-red version of MC1R or red version of MC1R gets a bit tiring after ~ awhile. So i will execute what geneticists do. Ns will call the non-red version of the MC1R gene R and the red variation r. I also used that naming mechanism in the figure.
None of their youngsters would have actually red hair yet they would certainly all it is in carriers because grandpa would certainly pass on his red hair gene. Every the kids have a non-red copy the the MC1R gene (R) from grandma and also a red copy (r) from grandpa -- they would all be Rr.
Let"s say among these kids is your mother and that her father wasn"t a carrier. In various other words, your mother is Rr and your dad is RR. Her mother has actually an equal possibility of passing either the red (r) or the non-red (R) variation to she kids.
Let"s say she happen the red hair variation to you. Due to the fact that your dad wasn"t a carrier, this means he passed only a non-red version (R) to you. So you are a carrier for red hair (Rr).
So now we have gone 2 generations without a redhead. Imagine the something similar happened on her husband"s side of the family.
Now here you are, both carriers because that red hair (Rr). As I claimed before, a carrier has actually an equal possibility of passing either copy that a gene come his or she child. So every of your youngsters has a 1 in 2 chance of getting a red hair version (r) native you and the same chance of acquiring a red hair variation (r) from her husband.
To number out the possibilities that you both will certainly pass an r down to her kids, you main point the chances together. This way that each child has a 1 in 4 chance of acquiring two r versions and also having red hair. The possibilities for this happening through both your kids are 1 in 16 (again simply multiplying the chances together).
To provide you part idea around how likely this is, it is about the same chance as flipping a coin four times and getting 4 heads in a row. Or the exact same as a household having four boys in a row. No the most usual outcome yet we"ve every seen households with kids of all one sex or the other.
See more: 1999 Ford Taurus Speedometer Not Working → Diagnosis, Speedometer Stopped Working (Ford Taurus)
So over there you have it. Recessive traits like red hair have the right to skip generations due to the fact that they can hide the end in a transport behind a dominant trait. The recessive properties needs another carrier and also a little bit of happy to it is in seen. This way that it have the right to sometimes take a couple of generations to ultimately make its presence known.