# Question regarding dominant and recessive genes **URL:** \ **Category:** Factual Questions\ **Created:** [November 2, 2013, 3:46pm UTC](https://boards.straightdope.com/t/question-regarding-dominant-and-recessive-genes/672928 "2013-11-02T15:46:34Z")\ **Posts on this page:** 6\ **Page:** 3
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [April 19, 2015, 7:43am UTC](https://boards.straightdope.com/t/question-regarding-dominant-and-recessive-genes/672928/41 "2015-04-19T07:43:45Z")
> [@Bill\_Grissom](#): > > Certainly, dominant and recessive is too simple to be the full story. Everything is a mixture. But, it is the simple explanation that Mendel used and a fine start for 9th-grade biology. So why can’t the books state it? Are all biologists really that clueless? It’s not that dominant and recessive is too simple to be the full story. The book I use for general science only goes into dominant and recessive inheritance, but it doesn’t say that’s the only game in town either, so there’s nothing inaccurate there, other than using examples that have been discovered to have a complexity that means they’re not 100 % exclusively dominant and recessive inheritance. What it doesn’t do is say “recessive represents a flaw or lack of information”, because that is just flat out wrong and not useful beyond creating a flawed belief of understanding. I have a hard time believing “different but weaker” which is accurate, makes things more difficult to grasp than “flawed and lacking in information”. And teaching something that is flat our wrong, rather than leaving out complexities, creates a barrier to further understanding. It’s much harder to unlearn something than to add more layers of understanding. And most students will never need to know the actual mechanisms of how various genotypes _actually_ turn into fenotypes. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [April 19, 2015, 2:50pm UTC](https://boards.straightdope.com/t/question-regarding-dominant-and-recessive-genes/672928/42 "2015-04-19T14:50:17Z")
> [@Bill\_Grissom](#): > > But, as the “sickle cell anemia” example proves “recessive statistics” can be caused by a dominant trait (too much of something), so simply noting dominant vs recessive doesn’t always help. In the end, you must dig into the details to find a cure, but I would first look for “something deficient” when the statistics are recessive. I hope this helps. I am just an engineer, and you guys are declared experts. I AM a declared expert. I am a biologist and geneticist. I am finishing up my PhD at the moment, and have taught genetics to Ivy League undergrads. You are severely misusing the terms “dominant” and “recessive”. You don’t understand what they actually mean, and you are conflating a variety of definitions in inappropriate ways. Dominant means “the version of the trait that’s visible in the heterozygote”. Recessive means “the version that’s not visible”. That’s IT. The end. There is no “too much of something” or “not enough of something” or “stronger” or “weaker”. ALL of that crap is completely wrong. I will say that this is a little bit flexible, in that it depends on how you define the phenotype. If the phenotype is “has sickle-shaped cells”, then sickle-cell anemia is recessive. If it’s “makes some hemoglobin with a neutral patch on the surface” then it’s dominant. ---
**Author:** ![dasmoocher](https://avatars.discourse-cdn.com/v4/letter/d/dbc845/32.png) [@dasmoocher](https://boards.straightdope.com/u/dasmoocher)\ **Post date:** [April 19, 2015, 3:32pm UTC](https://boards.straightdope.com/t/question-regarding-dominant-and-recessive-genes/672928/43 "2015-04-19T15:32:43Z")
> [@Bill\_Grissom](#): > > Please read and understand this before proceeding. > Certainly, dominant and recessive is too simple to be the full story. Everything is a mixture. But, it is the simple explanation that Mendel used and a fine start for 9th-grade biology. So why can’t the books state it? Are all biologists really that clueless? > > In the end, you must dig into the details to find a cure, but I would first look for “something deficient” when the statistics are recessive. I hope this helps. I am just an engineer, and you guys are declared experts. Here’s a clue: You can’t believe everything you read on the internet. You’re telling a crowd of people that might actually have a genetics-based background that a more careful reading is needed. Though, caveats abound, you can’t actually believe the stated research findings in every paper you find on PubMed, or the “Interrweb”, without having the background to evaluate the said claims of the paper. I imagine engineering research is not so different. ---
**Author:** ![Iggy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iggy/32/3364_2.png) [@Iggy](https://boards.straightdope.com/u/Iggy)\ **Post date:** [April 20, 2015, 4:46pm UTC](https://boards.straightdope.com/t/question-regarding-dominant-and-recessive-genes/672928/44 "2015-04-20T16:46:36Z")
My Bachelor’s in Genetics (UW '93, Go Bucky!) agrees with **Smeghead**. I know what dominant and recessive mean in terms of Mendelian genetics. And those terms have _nothing_ to do with such terms as “ineffective” or “weaker”. Recessive traits do not necessarily provide “no information” and may not be a “weak trait”, “nothing useful” or “ineffective”. Dominant traits are not necessarily “stronger” trait(s) (or at least “something”). Seriously, this is a board dedicated to fighting ignorance. **Bill Grissom** , for a basic primer on genetics you may wish to read a genetics text book. [The Cartoon Guide to Genetics](http://www.amazon.com/Cartoon-Guide-Genetics-Updated/dp/0062730991/ref=sr_1_1?s=books&ie=UTF8&qid=1429545975&sr=1-1&keywords=The+Cartoon+Guide+to+Genetics) by Larry Gonick and Mark Wheelis covers basic principles that you seem to be confused about. ---
**Author:** ![Bill\_Grissom](https://avatars.discourse-cdn.com/v4/letter/b/94ad74/32.png) [@Bill\_Grissom](https://boards.straightdope.com/u/Bill_Grissom)\ **Post date:** [April 21, 2015, 3:00am UTC](https://boards.straightdope.com/t/question-regarding-dominant-and-recessive-genes/672928/45 "2015-04-21T03:00:58Z")
I did a bit more reading, and my statement that recessive traits come from “lack of information” is usually true, but not always (like most things in science). It certainly is true in the case of blue eyes (or blue iris), which come from lack of melanin (i.e. information in the chromosomes to produce melanin there as the baby develops). wikipedia has a detailed article on eye color. That was my original example, and Cecil Adams answer, and the main example I recall from grade school. To be exact, there are other things that affect eye color beside iris melanin. There is backing behind the iris which in the case of albinos is clear, so you see the retinal blood, thus appearing pink. Research other traits, ex. detached vs attached ear lobes (I haven’t) and you may find the recessive trait comes from missing information. Has anyone explained Mendel’s round vs wrinkled peas? Don’t most genetic diseases come from missing something, like inheriting 2 defective instructions? A quick read says that cystic fibrosis is such. Sickle-cell anemia is a bit unusual, and an oft-quoted example of “heterozygote advantage” or “over-dominance” (per wikipedia) where the half-way mixture is “just right”, but only if you live where the population must ward off malaria. These raise questions of evolutionary advantage. There is much speculation as to why the genes which lead to cystic fibrosis have persisted. In some mixtures they may give some advantage to people living (now or in the past) in Northern Europe. Regardless, you guys keep delving into the minute details to scream “wrong”. My point is that in many well-known cases (blue vs brown eyes) there are simple explanations as to why one is a recessive trait. Why keep that from students in 9th grade? Should we not teach F=mA in introductory Physics because in the deepest version, it is not correct (assuming special relativity is correct)? Much good has come from using F=mA. Suspecting recessive =\> something missing may lead to cures for diseases that have a genetic basis, and apparently already is. At a minimum, I have gotten you to think more and discuss, even if much of it is (unthought) “you’re a fool” claims. Teaching is an excellent way to clarify your own thoughts. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 21, 2015, 3:20am UTC](https://boards.straightdope.com/t/question-regarding-dominant-and-recessive-genes/672928/46 "2015-04-21T03:20:14Z")
Science is _all about_ the details. We _should_ be delving into the minute details to call something “right” or “wrong”. [Previous page](https://boards.straightdope.com/t/question-regarding-dominant-and-recessive-genes/672928.md?page=2)