Naked Science Forum

Life Sciences => Physiology & Medicine => Topic started by: katieHaylor on 14/09/2017 12:09:51

Title: How genetically similar are we to our family?
Post by: katieHaylor on 14/09/2017 12:09:51
Ken asks:

Who is my closest genetic relative? My parents? My children? My siblings?

What do you think?
Title: Re: How genetically similar are we to our family?
Post by: chiralSPO on 14/09/2017 15:09:24
Well, if you have an identical twin (or more) than they are the closest relative(s).

Whether you are a girl or a boy (more so for girls), you are probably least genetically similar to your father, because all children inherit their mothers' mitochondrial DNA. Also the X chromosome is substantially longer than the Y, so even a boy would have more genetic material from his mother than his father (not counting mitochondrial DNA).

Beyond that, *I'm* out of my league. There are probably others on the forum who can give even more nuanced answers.
Title: Re: How genetically similar are we to our family?
Post by: smiguel on 15/09/2017 12:16:49
And after an identical twin, the closest genetics are

your parent and
your children
Title: Re: How genetically similar are we to our family?
Post by: evan_au on 16/09/2017 08:52:52
While your chromosomes are a selection that comes from your parents, they are not identical to the chromosomes that your parents carry.

During DNA copying, there is a finite probability of making a copying error, which may result in one amino acid being substituted for another.

During meiosis, "crossovers" can occur:
- The two chromosomes line up before the crossover, so you end up with 1 chromosome which is a hybrid of two chromosomes carried by your parents.
- But the lineup isn't exact
- If the break is in the middle of an active gene, the resulting gene may be mutated, with some base pairs omitted or duplicated. This may inactivate the protein produced by the gene.
- If the alignment is particularly poor, you may end up with multiple copies of a gene, or several genes omitted.

In most cases, the errors can be overcome by proteins generated from the chromosome inherited from your other parent, as it is unlikely that exactly the same protein will be mutated.

These types of mutations are best found by "triple sequencing": reading your genome, plus those of your parents, and comparing them to see where the mutations have occurred.