Incest - Right Or Wrong?

[suedonim]

I was quite intrigued to read this story about two siblings in Germany who are seeking to overturn the laws on incest. Are their civil rights being breached or is the law there for a good reason?

dunno did they?

"yuk" is probably the least offensive of things I might have said. The made their choices, and the children have to to live with them. That doesn't seem just.

I thnk rabbits mate with siblings.

I'm not sure I'm right about this, but I think it isn't such an issue for animals becuase their genetic make-up is much more simple than ours - they have far fewer genes or chromosomes or something.

I see, so there's less to go wrong

I think so. We need to ask tamum - she is the genetics expert.

Just for the record, I wasn't suggesting it was right or good. I would not do this with my own brother, in case you were wondering

So if this couple were YOUR children or relatives, would you ostricise them from your family and friends ? Would you make sure they were punished for the rest of their lives for the mistakes they have made ?

It is done. They have children. People need to help them not yuk them.

No, animals are no less complex genetically than humans, but the reason most of them get away with it is, I imagine, that they're already so inbred that most bad mutations have already been selected out.

Here's what I said yesterday on the other thread about this:

We are all on average carriers for 10 recessive diseases, so the chances of a brother/sister pairing resulting in defects are really quite high. With my geneticist's hat on I would say that this was A Bad Idea, but with my pinko liberal one on I would say they should be left alone. I don't think taking the children into care is going to achieve anything other than to increase the chances of this happening again in the future, and that really would be a bad idea.

Another point, to back up what suedonim said, is that the medical literature is full of disease genes that have been isolated because first cousin marriages are common in some parts of the world- it's like a treasure trove for geneticists, but not so hot for the people concerned, obviously. I do think it goes to show that incest really does lead to genetic problems.

Oh - sorry I was wrong. Why did I think that dogs had twice had twice as many genes as cats, or vice versa?

Probably because my genetic make-up has the same complexity as a tadpole.

Sorry No idea really- maybe different numbers of chromosomes, but we have pretty much the same number of genes as mice and not that many more than fruit flies, so I think cats and dogs would be the same.

Different sorts of animals often have different numbers of chromosomes, but I don't think that makes these sorts of problems less likely.

Tamum, there must be some recessive problems with animals, surely? Things like sickle cell, that give an advantage when you're a carrier, and are only a problem when you have it on both sides?

But then again, wild animals are presumably largely used to a significant number of their offspring not surviving infanthood anyway, so (greater) inbreeding is maybe unlikely to make things worse?

(OT: tamum, can I ask for your input here ? It's in your other area of expertise ...)

Oh yes, of course they carry recessive mutations unless they're really inbred, like strains of mice, but in the wild they just wouldn't survive anyway mostly, would they.

another reason why repeated cosanguinous marriages is a bad idea is that you significantly limit the number of people that you can use as organ donors.

Marriage of cousins is a common practice in parts of Pakestan and bangladesh (not all areas, but in rural areas it is very common). These people ae now beincoming more and more similar in terms of genetic markers. Asian people are also more prone to hypertension and diabetes and damage to their kidneys. These people, if they need a new kidney,will need a good match (as do all recipients) but they have a much smaller pool of potential matches to 'call upon'.

Marrying 'out' is always a good idea.

and as an aside Tamum, I had to teach the upper sixth form the Hardy Weinburg equation today.

OMG! but we got there in the end!

PS one of my lower sixth got 99/100 in her first module!, out of the top set of year 12s over half of them got A grades, I was well chuffed!

You are an absolute star teacher, you are

What I find particularly disconcerting about this story, is that by the time she was 19 or 20, they had already had four children together.

Marriage to first cousins was also a very common practice throughout the West for most of history. Our royals did it. It is never a good idea.

To be fair to these kids, they are so good you could lock them in a wardrobe with a book and a torch and they would still get an A grade.

In fact, one was up in Edinburgh yesterday looking round the Dick Vet. I should have sent her to you, she is a real super star!

If only I had had such teaching...I may not be languishing in ignorance as an arts grad!

Well done, MB - what is the Hardy Weinberg equation?

"To be fair to these kids, they are so good you could lock them in a wardrobe with a book and a torch and they would still get an A grade"

Yeah, right Now let's see you explain Hardy Weinberg to Blu....

oh god, you are giving me flash backs!

They are a pair of equations that let you work out how common genes are in a population. There are some limits on when you can use it. But what you do is count how many people in the community actually show a recessive trait.

Imagine that giantism is a recessive trait. To be a giant you have to have two copies of the recessive gene. gg. GG people are of 'normal' hight, as are Gg people who carry the gene for giantism, but are 'normal' hight themselves.

Ok the equartions say

p + q =1 the frequency o the dominant gene= p= G and the recessive gene q =g must added together = 1 or 100% of the genes available.

and p2 + 2pq + q2 =1

where p2 is the number of people who are GG 2pq= the number of people who are Gg and q2 is te number of people who are gg.

Hagrid is the only giant in Hogwarts out of 100 people

q2= 1/100

so the frequency of the gene is root 1/100

once yuo know that you can work out all the other frequencies by simple maths

You see - 12 minutes googling the resources of all the teasching on the www and I was utterly mystified. 2 mins reading MB's explanation, and I understand!

There must be an equation to show the increased effectiveness of MB's explanations over the rest of the world!

Message withdrawn

oh is that so?
(to PRuni, tamum, mb et all)
good grief isn't mumsnet educational?