🚀 go-pugleaf

In article <009354F6.2C3AB780@MV3600.BMEN.TULANE.EDU> ramesh@MV3600.BMEN.TULANE.EDU (Ramesh Srinivasan) writes:
>>1. I have heard when two close relatives get married, their children
>>   will have a great chance of having defective genes.
> Comment:
>	I have been pondering this very issue in relation to my kittens
>They are from the same litter, and will probably mate when they reach maturity
>(my family cats did the same thing)  

*sigh* Once again:  the problem is recessive genes.  If a dominant gene
causes something not conducive to reproduction, it will not survive out
(this is pretty obvious to most people).  However, a recessive gene does not
have that problem, and, in fact, is the ideal way to spread some trait (the
idea being that, after enough time, enough of the population will have the
recessive gene that their children will show the trait).  For example:  did
you know that the gene(s?) for six-fingeredness (forget the name, sorry) are
dominant?  Yet most people have five fingers.  Perfect example, don't you
think?

Now, a recessive gene, of cours, needs to be paired up before it can
manifest itself.  Since siblings are both likely to have a recessive gene
(assuming it is not a sex-linked gene), then there is a 25% chance that the
offspring will have both genes, thus manifesting it.  Since most people have
more than one recessive gene, a whole slew of undesirable traits may show
up.  Thus, incest is not good.

Now that that's all said, we go onto the fine tradition of animal husbandry.
Not all recessive genes produce undesirable traits; an equally large number
produce desirable traits (and a probably larger number produce results
nobody cares about 8-)).  Therefore, to get the trait, you need to breed
siblings to demonstrate it, and then keep breeding until all of your
breeding pool shows it.  Ugh.  I can't remember an example right now, but
let's say that manxism in a cat (you know, no tail?  A Manx cat, that is)
were recessive (I don't think it is, but I don't know for certain).  Now,
let's say that you wanted Manx kittens, and you had two cats, male and
female, who had a tail, but you knew to have a recessive manx gene.  So, to
get your manx cats, you would breed the two cats.  Of the kittens that had
no tail, you would first cull the obvious defects (if any at this point).
Then, you breed them.  All of the kittens, at this point, will be manx
(since there are no non-manx genes).  However, you will need to "cull" the
defects (i.e., kill them, probably.  Messy job, I'm afraid), because there
will be some other non-desirable trait (such as stillborness, possibly) that
you would like to get rid of.

Keep at this for a couple of generations, and you have healthy cats, sans
tail, that you can sell.

Naturally, usually when this is done, the trait isn't something as trivial
as that, and, usually, the breeder is going for a combination of traits,
which is why you breed sibling with sibling.

*Whew*!  That was *long*.  Hope it made sense, though.

>By allowing them to mate, keeping a male and female kitten and allowing them to
>mate, the propogation of defective genes can be studied thoroughly since I will
>be able to witness at least 30 cat generations.  If we can obtain some funding
>(at least the price of cat food) I am prepared to carry out these experiments

I hope you are not a sqeemish person.  This is an extremely unpleasant job
you're undertaking.  If there are certain types of traits in the family, a
good portion of the kittens will be stillborn, if you're lucky.  Other ones
will be killed by the mother, for various reasons (mother cats will kill
kittens that are too sickly, under some circumstances), and you may have to
kill them yourself, if she doesn't.  Unless you want blind and deaf cats, in
which case I question you as a human being.

>>2. What about two persons with same last name but are not relatives at
>>   all.   Will they face the same risk?
>>Comment: 
>	This idea is simply moronic!!!!!!!!!!!!!!!!!!!!!!!

True.  And this person is going to write a *paper* about genetics?  Tsk,
tsk, tsk...

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Sean Eric Fagan  | "It's a pity the universe doesn't use [a] segmented 
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