182
Why does incest result in birth defects?
(lemmy.world)
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
this post was submitted on 05 Feb 2024
182 points (96.9% liked)
No Stupid Questions
34292 readers
2069 users here now
No such thing. Ask away!
!nostupidquestions is a community dedicated to being helpful and answering each others' questions on various topics.
The rules for posting and commenting, besides the rules defined here for lemmy.world, are as follows:
Rules (interactive)
Rule 1- All posts must be legitimate questions. All post titles must include a question.
All posts must be legitimate questions, and all post titles must include a question. Questions that are joke or trolling questions, memes, song lyrics as title, etc. are not allowed here. See Rule 6 for all exceptions.
Rule 2- Your question subject cannot be illegal or NSFW material.
Your question subject cannot be illegal or NSFW material. You will be warned first, banned second.
Rule 3- Do not seek mental, medical and professional help here.
Do not seek mental, medical and professional help here. Breaking this rule will not get you or your post removed, but it will put you at risk, and possibly in danger.
Rule 4- No self promotion or upvote-farming of any kind.
That's it.
Rule 5- No baiting or sealioning or promoting an agenda.
Questions which, instead of being of an innocuous nature, are specifically intended (based on reports and in the opinion of our crack moderation team) to bait users into ideological wars on charged political topics will be removed and the authors warned - or banned - depending on severity.
Rule 6- Regarding META posts and joke questions.
Provided it is about the community itself, you may post non-question posts using the [META] tag on your post title.
On fridays, you are allowed to post meme and troll questions, on the condition that it's in text format only, and conforms with our other rules. These posts MUST include the [NSQ Friday] tag in their title.
If you post a serious question on friday and are looking only for legitimate answers, then please include the [Serious] tag on your post. Irrelevant replies will then be removed by moderators.
Rule 7- You can't intentionally annoy, mock, or harass other members.
If you intentionally annoy, mock, harass, or discriminate against any individual member, you will be removed.
Likewise, if you are a member, sympathiser or a resemblant of a movement that is known to largely hate, mock, discriminate against, and/or want to take lives of a group of people, and you were provably vocal about your hate, then you will be banned on sight.
Rule 8- All comments should try to stay relevant to their parent content.
Rule 9- Reposts from other platforms are not allowed.
Let everyone have their own content.
Rule 10- Majority of bots aren't allowed to participate here.
Credits
Our breathtaking icon was bestowed upon us by @Cevilia!
The greatest banner of all time: by @TheOneWithTheHair!
founded 1 year ago
MODERATORS
I'll try to keep it relatively simple - your cells contain chromosomes that contain your genes. You usually* have two sets of every chromosome.
These genes come in different variations/mutant forms called alleles. Most alleles function more or less the same, but some malfunctions result in deformities.
If a malfunctioning allele results in errant gene inactivation, it is known as recessive, which means as long as your other copy works, you're all good.
If a malfunctioning allele results in an errant gene activation, it is known as dominant, which means if you have the allele you get the deformity regardless of if your other copy works or not.
Fortunately for life, most malfunctioning alleles are recessive, so as long as you've got high genetic variance (a lot of alleles) in a population, the chance of two people meeting with the same recessive malfunction is low.
Incest can result in a drastic decrease in genetic variation, which can result in malfunctioning alleles becoming much more prevalent than they usually would be, resulting in many more cases of recessive deformities than in the wider population.
*For males this is not true of their sex chromosomes. Many genes present on the X chromosome are missing on the Y chromosome, which can lead to sex exclusive traits and diseases.
For example, it is the reason why there are almost no calico/tri-colour male cats, as the genes for it are in X but not Y chromosomes.
And the male calicos that exist actually have Klinefelter syndrome, where they wound up with an extra X chromosome, making them XXY instead of XY.
And so the reason for malfunctioning alleles not to be dominant is probably natural selection. E.g. you select away bad dominant alleles, but if we assume a low pct of inbreeding, the recessive ones are irrelevant and so they stay.
Pretty much...
Recessive malfunctions can hide away amongst carriers for generations before manifesting any deformities, during which time they have no effect on the carrier's survival, so there's very little selective pressure against them.
Dominant malfunctions which cause deformities simply can't hide away, so have enormous selective pressure against them.
Interestingly enough though, there are times where dominant malfunctions can survive that pressure...
For example, having Sickle cell disorder increases your resistance to Malaria, so even though the full form is rarely passed on, the single allele form (which caused partial disorder) is passed on due to a slight positive selection pressure.