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Incest

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Kingbarney
303448.  Wed Mar 26, 2008 5:29 pm Reply with quote

I know this a huge taboo but I am sure that not much known in the general population about this topic either. What I would like to know, is what is the known genetic effects of Incest among humans ?

 
Fifi
303516.  Wed Mar 26, 2008 6:41 pm Reply with quote

As far as I understand it, mutation.

I don't think this often happens first go round as it were - but once after a prolonged limited gene pool.

I'm not sure exactly how it happens but I think it is something to do with recessive genes not being worked out as it'll end up that every person has them and so therefore the changes of people having whatever is recessive. I think also there can be random mutations.

I'm sure that looking at the Egyptians would be a good start.


*awaits klaxons on all the above points!*

 
Jenny
303519.  Wed Mar 26, 2008 6:45 pm Reply with quote

Wikipedia says:

Quote:
Inbreeding leads to an increase in homozygosity (the same allele at the same locus on both members of a chromosome pair). This occurs because close relatives are much more likely to share the same alleles than unrelated individuals. This is especially important for recessive alleles that happen to be deleterious, which are harmless and inactive in a heterozygous pairing but, when homozygous, can cause serious developmental defects. Such offspring have a much higher chance of death before reaching the age of reproduction, leading to what biologists call inbreeding depression, a measurable decrease in fitness due to inbreeding among populations with deleterious recessives. Recessive genes, which can contain various genetic problems, appear more often in the offspring of procreative couplings whose members both have the same gene. For example, the child of persons who are both hemophiliac has a nearly 100% chance of having hemophilia.

 
AlmondFacialBar
303520.  Wed Mar 26, 2008 6:47 pm Reply with quote

it's the recessive genes that come to the forefront there. basically, a recessive gene, if only expressed once in a person's genome, will not cause any change to their phaenotype, good, bad, or indifferent, so even with a defective recessive gene the person will not actually be sick.

what happens in cases of incest is that, with both partners being from the same family, there is a larger chance they're sharing genes than there would be with non-related partners, and hence there is also a higher chance they share a defective recessive gene. hence that gene would than be expressed twice in the offspring who would then suffer from the associated disorder.

in a nutshell, the offspring of incestous relationships has a higher risk of genetic disorders for that reason, but that's it.

:-)

AlmondFacialBar


Last edited by AlmondFacialBar on Wed Jun 15, 2011 3:51 pm; edited 1 time in total

 
djgordy
303521.  Wed Mar 26, 2008 6:50 pm Reply with quote

Fifi wrote:
As far as I understand it, mutation.


Incest and inbreeding doesn't in itself cause mutations. It just means, basically, that mutations which occur naturally become more prevalent in a restricted breeding population than they would in a unrestricted breeding population.

There is a good explanation of inbreeding and the associated problem of genetic drift here.

http://www.ucl.ac.uk/~ucbhdjm/courses/b242/InbrDrift/InbrDrift.html

 
CB27
303944.  Thu Mar 27, 2008 8:03 am Reply with quote

It's a perfect example of how evolution works.

People mention mutations, but what they mean is adeformity because these "mutations" from incetous family lines tend to come about from recessive genes benig given ever greated exposure.

Mutation is actually a positive thing and is a great driving force for evolution because it was mutation which led to the various body parts and functions we have today and even to the development of our brains.

If a mutation leads to a positive effect, it's likely that the carrier of that mutation is sought by members of the oppositie sex to breed and over time family lines of those who do not carry this mutation may probably die out.

 
grizzly
304153.  Thu Mar 27, 2008 12:23 pm Reply with quote

A couple of interesting articles I read on this topic. Firstly, one in the new scientist about 2 years ago discussing conservation programs for species of animals with very low numbers. It suggested that allowing inbreeding would not be a serious issue. Since most species have gone through or have a recent ancestor that went through a population squeeze, the resulting inbreeding does not create as serious a genetic problem as believed and that therefore moving animals around in captive breeding programs is not worth the effort.

A second article I read recently in the economist discussed research from the extensive family records in Iceland (that can allow most people native to the country to trace their family history back as far as 900AD) to examine population growth and the birth rate. One of its intriguing findings is that the optimum pairing for the having the greatest number of children in a family is between 3rd or 4th cousins (that is to say someone descended from a sibling of one of your great, (great) grandparents). This would suggest that your most compatible partner is one of your 3rd or 4th cousins because there is sufficient genetic diversity combined with some genetic benefits of sharing a common ancestor. The research in question went on to theorise that declining fertility rates are associated with urbanisation because the mixing up of people prevents you from meeting up with your distant relatives.

Here's the article in question.

 
Tas
304155.  Thu Mar 27, 2008 12:25 pm Reply with quote

Quote:
in a nutshell, the pffspring of incestouys relationships has a higher risk of genetic disorders for that reason, but that's it.


Are typing skills and spelling the first to suffer???

:-D

Tas

 
grizzly
304158.  Thu Mar 27, 2008 12:27 pm Reply with quote

BTW, according to the research discussed above, my perfect partner either lives in Glasgow or somewhere in the region of West Berks, South Oxfordshire and East Wilts...

 
samivel
304172.  Thu Mar 27, 2008 12:45 pm Reply with quote

That's me out then. Ah well.

 
AlmondFacialBar
304209.  Thu Mar 27, 2008 1:22 pm Reply with quote

Tas wrote:
Quote:
in a nutshell, the pffspring of incestouys relationships has a higher risk of genetic disorders for that reason, but that's it.


Are typing skills and spelling the first to suffer???

:-D

Tas


that one would have worked better if my parents were even from the same locality. they aren't. not a huge chance of incest there i'm afraid, old bean. ;-) blame the fact that i was posting that lying on the floor while wondering if my undergrad crush was back on.

:-)

AlmondFacialBar

 
Kingbarney
304275.  Thu Mar 27, 2008 2:56 pm Reply with quote

Thank you grizzly and djgordy for the articles very informative.

 
maiden
304384.  Thu Mar 27, 2008 4:11 pm Reply with quote

There's a programme on Channel 4 (9pm) about incest (That's if you live in Britain or get 4OnDemand on the internet that is!!!)

Might be worth watching to see if it comes up with any answers for you

 
Kingbarney
304388.  Thu Mar 27, 2008 4:21 pm Reply with quote

Today ? I'll watch it on the plus one channel.

 
maiden
304389.  Thu Mar 27, 2008 4:23 pm Reply with quote

Kingbarney wrote:
Today ? I'll watch it on the plus one channel.


Yes, today - the programme is on now (and plus1 later.... obviously, LOL)

 

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