Is your ancestor always genetically related to you?

Question

I read an article that states all blue eyed people have a common ancestor. I have brown eyes but eyes but my grandmother had blue eyes and thusly this common ancestor was her ancestor. Even though I dont have blue eyes since my grandmother did is this common ancestor my ancestor as well or is blue eyes like his only genes left after all these generations?

Answer 1

Yes.  In fact, every single human on the planet shares a common ancestor, if you go far enough back.

Answer 2

The correct answer is no.  For humans, and all other animals that reproduce sexually, the only ancestors that must be genetically related to an individual are the parents.  

Let's take an example to illustrate the point.

You receive half of your chromosomes from each parent.  When your germinal cells produce either sperm cells or eggs, these have half of the chromosomes of your other cells.  In the division process, it is possible (not likely) that all of the chromosomes in the sperm or egg are the ones from only one parent.  These will then combine with chromosomes from someone else so that your children may have half of their chromosomes from only one of your parents and the other from your mate.  That is, a given grand parent has a non-zero probability of having a grandchild with whom he/she shares no chromosomes.

For a human with 46 autosomes and 2 s*x chromosomes, the probability of having a given grandchild  with none of his/her chromosomes is 1/(2^26),  a small number. However, each reproduction cycle cuts down the expected number of shared chromosomes by half.  That means that after many generations, the expected number of chromosomes shared with a given ancestor goes down by half.  Eventually, after many generations, the expected number of chromosomes shared with a given ancestor approaches zero.

Answer 3

We all have the same ancestors.  I think that you are really asking about gene expression having a common ancestor.

Answer 4

Do some reading on "Mitochondrial Eve"...not only do people with blue eyes have a single common ancestor, but every person alive today can be traced to one single "mother" aptly named Mitochondrial Eve.

Answer 5

yes. there are recessive genes and there are dominant genes. you received the dominant brown gene. your grandma had the recessive blue gene.

like if one parent gave a brown gene and the other gave blue, the kid will have brown eyes. however, the blue gene will stay in the kid's "system" and be available for his own future kid. only if both parents gave blue genes  will the kid have blue eyes.

Answer 6

Yes ancestors are genetically related to you.