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can you breed a half sister and brother?

post #1 of 15
Thread Starter 
I have a question for experienced breeders. Can you breed a half brother and half sister? I was told that they do that in Europe all the time. I'm very confused on this matter. The reason I'm asking is someone sold me a cat and when she sent me the papers, I noticed that She has the same father as my stud. I was very upset. She then told me that they breed like that all the time in Europe. And that she would do it. I don't want to do something like that unless it is okay. I don't want to have a litter of defected kittens. I would really appreciate any help with this matter.
post #2 of 15
I'm not a breeder but I would consider breeding two cats who have the same father, very wrong. The only time I have heard something similar being done is when a mother is mated to her son when the breed is in danger of dying out.

I'm sure members who are much more experienced with this, will come along to answer your question soon.
post #3 of 15
I have never heard of it so I cant say, but from a purely genetic standpoint that we hear about with people and even other animals, its not something I would do except maybe to mice.. (sorry any mice out there that get offended).
post #4 of 15
Thread Starter 
thats what I'm thinking too. But this breeder is telling me it's okay. I'll have to ask my vet.
post #5 of 15
Considering that the Inbreeding Coeffecient is about 50% (could be more, but not much less) I wouldn't breed them regardless of what other breeders do. You have to remember that not only does that bring out the good qualities in the cats, but it also intensifies the bad.. so much so that you might end up with a genetic fault that wouldn't otherwise occur.

We never breed anything together with an IC of 19% or greater, and even then it's rare.

Now I know this might get you a little mad, and I don't intend for it to, but shouldn't you have looked over the pedigree before you purchased the cat?

I ask only because someone else is bound to, and it makes a good learning tool for breeders who are just getting started.

There are tools on the internet to calculate Inbreeding Coeffecients, and many of them are free. Do a search on google for it, as well as alot of info about it.

I know there are people out there who will disagree with me, and that's okay, but like I said, I would never do it.
post #6 of 15
Thread Starter 
Thank you very much. I didn't think I had to look over the papers before I purchased her. I just assumed that she sold me the stud. And that where she has been breeding for so many years that she would know better. But it seems she screwed me over. It's okay. Because she sold her to me pregnant. So after she weans her babies and they are sold. I will spay her and keep her as a pet. Thank you for your help.
post #7 of 15
I agree with Ken, it is very wrong to breed close relatives line. Cat will be with some defects, like heart defect, etc. Better stay away from that.
post #8 of 15
Thread Starter 
I am definately going to stay away from that. I'm really upset that she took advantage of me. Next time I will investigate much further before purchasing a cat. However, I am getting a litter out of her from another male. They are going to be gorgeous. I'll just have to find my stud a new woman. LOL.
post #9 of 15
I wonder if breeding one of her female offspring with your stud would be far enough away to be OK? I'm not sure...
post #10 of 15
Thread Starter 
I never thought of that. I really need to look into it alot further. I've heard that you can breed a father to a daughter and mother to a son. I certainly wouldn't want to mess up their genetics.
post #11 of 15
While some breeders do closely line-breed, it is not done at all often by the majority of those who consider themselves to be responsible and ethical. That now being said, there ARE ~sometimes~ good reasons to go ahead with it. Sometimes, that line carries a particularly attractive trait which can only be replicated by closely line-breeding cats with the identical trait.

But, based on the information you've given us here and the lack of complete familarity of your stud's pedigree, I might pursue an unrelated line as a suitable outcross.

Just a thought,

post #12 of 15
We do line breeding father/daughter half brother/sister on occasion but never mother/son. I don't reccomend breeding this close though. We have only had one problem occur and that was father/daughter.
post #13 of 15
Thread Starter 
When a cat is mated with a halfsister / halfbrother the IC is 12.5 % I got this off the Norwegian info site.
post #14 of 15
My point of view (I'm a European breeder) is that inbreeding is unnecessary. Everything closer than cousins is unthinkable and I always strive for 0 % inbreeding. Maybe I have this opinion because I'm breeding a breed that have been severly damaged by inbreeding. I've never seen reasons good enough for breeding to cats closer related than cousins. That being said maybe I should mention that we actuarally use other breeds to expand the genepool of the Devon Rex, instead for using inbreeding. Uring inbreeding have been tried but it resulted in more cases of primary myopathy, naked cats, small cats and small litters... what "we" (I was active in breeding then) probably never saw was their immune system collapsing but that often happens when a population goes through an inbreeding depression.

I've seen the bad sides of inbreeding and that made me decide never to use that method myself. Inbreeding is, I think, just a short cut to a better typed cat, but I strongly believe that it's on the cost of the breeds health and longevity.
post #15 of 15
Originally Posted by javajane
When a cat is mated with a halfsister / halfbrother the IC is 12.5 % I got this off the Norwegian info site.

This is true of the offspring. I should have been clearer on this.
We breed to what the IC is of the parents in relation to the other, not what the offspring would be.
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