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Author Topic: How far back in my family history do genetic traits go?  (Read 6665 times)

Offline colarris

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When it comes to inheriting family traits from a previous generation how far can the genetic history go back to? Do my genes store traits from every generation in my families past?
« Last Edit: 30/07/2013 15:56:40 by chris »


 

Offline RD

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Re: Genetic traits
« Reply #1 on: 25/07/2013 07:32:15 »
When it comes to inheriting family traits from a previous generation how far can the genetic history go back to?

At least a couple of hundred thousand years ... http://en.wikipedia.org/wiki/Mitochondrial_Eve


Further back than that if you don't restrict your ancestors to human ...
Quote
Molecular evidence shows that some limited number of Hox genes have existed in the Cnidaria since before the earliest true Bilatera, making these genes pre-Paleozoic
http://en.wikipedia.org/wiki/Homeobox#Hox_genes
« Last Edit: 25/07/2013 07:49:43 by RD »
 

Offline CliffordK

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Re: Genetic traits
« Reply #2 on: 25/07/2013 08:43:44 »
You could also look at it this way.

How much of your father's genes do you carry?
1/2 Paternal genes, 1/2 of the Maternal genes.

You Grandfather's genes?
1/4

Great Grandfather's genes?
1/8

And so on and so forth.  After 100 generations, the total amount inherited from any single ancestor is mighty small, although undoubtedly there would be some inbreeding in 100 generations so a single individual might contribute to multiple branches of a family tree.

There would be some exceptions to the rule. 

For a male, you can follow the Y chromosome back through each successive male generation (father, grandfather, great grandfather, great great grandfather, etc) with essentially 100% inheritance (plus the occasional random mutation).

Likewise, you can follow your mitochondrial DNA through successive female generations (Mother, grandmother, great grandmother, etc) with essentially 100% inheritance (plus random mutations).

That means that genetic diseases or conditions on the Y chromosome and Mitochondria also have a very simple inheritance pattern. 

Some X-associated conditions like baldness can be generation skipping, being passed from the Maternal grandfather to the son, skipping the mother.

Some human traits such as skin color involve several genes, and tend to follow a dilution pattern of inheritance.

You will, of course, have inherited all your genes (except those with new mutations) from at least one ancestor....
 

Offline colarris

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Re: Genetic traits
« Reply #3 on: 25/07/2013 10:08:20 »
Thats great, thanks for the info.
 

Offline CliffordK

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Re: Genetic traits
« Reply #4 on: 25/07/2013 19:23:46 »
If there were no crossovers...  And you have 46 chromosomes (23 pairs), then once you had 46 ancestors (6 generations gives 64 ancestors), some of the ancestors would not be donating whole chromosomes.

However, during meiosis, crossovers allow the new chromosomes to be composites of the old ones so you are still a composite of all your ancestors (except, as mentioned the Y chromosome and Mitochondrial DNA are passed through the paternal and maternal lineage).
 

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Re: Genetic traits
« Reply #4 on: 25/07/2013 19:23:46 »

 

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