2010-12-09, 16:28
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#307
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廉頗
Join Date: Feb 2004
Location: Massachusetts
Age: 34
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Quote:
Originally Posted by karice67
No, given your explanation here, you've worded it correctly. But the understanding you have of the subject, as indicated by the bolded phrase, is incorrect. I'll try to explain - there will probably be some slightly incorrect wording because it gets complicated otherwise.
Spoiler for going OT:
The original pool of DNA, which makes up the genes that the parents have, is the same. Each parent has two sets of the same genes (each version of a gene is called an allele). Putting it correctly, each parent has two alleles for each gene. A child of these parents would inherit one allele from each parent for each gene (activation doesn't have anything to do with the situation at this point), therefore, 50% of his/her DNA is definitely from one parent, and the other 50% is from the other. But different children may inherit different alleles from each parent for a particular gene.
If we look at just two genes A and B, say the father has the alleles A1 and A2, and B1 and B2. Any children he has may inherit his DNA for these genes in the following combinations (they only inherit one allele per gene from each parent, thus they cannot inherit both A1 AND A2, for example):
A1 and B1 => Child 1
A1 and B2
A2 and B1
A2 and B2 => Child 4
As you can see (Child 1 and Chid 4), it's possible for siblings to have no paternal DNA in common for these two genes. It is also possible that both siblings will inherit the same combination of alleles from their father for these two genes. However, it is highly unlikely (if you understand probabilities, I'm sure you can see why) for them to inherit exactly the same set of alleles from their father AND exactly the same set from their mother, unless they are identical twins.
Hence, they DO NOT have identical genetic makeup, which is what you said in your earlier post on the subject.
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But by genetic makeup I meant potentially inheritable DNA. What I misperceived was that even the genes not inherited would still be stored in the person, which is not true.
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