# Heritability of a physical defect caused by in-utero environmental poisoning **URL:** \ **Category:** Factual Questions\ **Created:** [August 2, 2008, 6:34pm UTC](https://boards.straightdope.com/t/heritability-of-a-physical-defect-caused-by-in-utero-environmental-poisoning/458621 "2008-08-02T18:34:41Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [August 2, 2008, 6:34pm UTC](https://boards.straightdope.com/t/heritability-of-a-physical-defect-caused-by-in-utero-environmental-poisoning/458621/1 "2008-08-02T18:34:41Z")
Are physical and/or mental defects caused by the environmental substances that impact the developing fetus like certain drugs or alcohol etc heritable at all? For example if a woman born with fetal alcohol syndrome has a child (with a standard no drinking no drugs pregnancy), is that child at any higher risk for FAS related birth defects due to her FAS birth defects. I guess I’m asking if birth defect is the result of an environmental aggressor or poison is that birth defect locked in your genes for ever after or not? ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [August 2, 2008, 6:54pm UTC](https://boards.straightdope.com/t/heritability-of-a-physical-defect-caused-by-in-utero-environmental-poisoning/458621/2 "2008-08-02T18:54:17Z")
[QUOTE=astro] Are physical and/or mental defects caused by the environmental substances that impact the developing fetus like certain drugs or alcohol etc heritable at all? For example if a woman born with fetal alcohol syndrome has a child (with a standard no drinking no drugs pregnancy), is that child at any higher risk for FAS related birth defects due to her FAS birth defects. I guess I’m asking if birth defect is the result of an environmental aggressor or poison is that birth defect locked in your genes for ever after or not? [/QUOTE] Big question, but I would think generally no. FAS specifically, looks like it’s a special case of alcohol poisoning/overdose affecting the developing nervous system of the unborn baby. Has no effect on anybody’s genetics. Under the circumstances you describe I would think the risk for any kind of FAS to her own child would be near zero. If the environmental substance is a mutagen, however, a substance that does affect genes, then the children of a person exposed in utero could indeed have birth defects. In fact, I believe that the effect would be stronger, or different, for the child conceived and born long after the exposure, because of the way mutagens work individually on different cells in the body. Generally, that is, mutagens tend to have a somewhat random effect on each cell that they affect. For an adult, this means that any one mutant cell will probably not reproduce to much of their body unless it’s mutated in such a way that its replication controls turn off - a cancer cell. They might get a large number of their cells mutated in different ways or dying off because their mutant nature is not survivable - radiation sickness is the term for this if the mutagen is radiative, I’m not sure if there’s an equivalent for other mutagens. For an embryo, each mutated cell will probably divide much more because every cell in a developing embryo replicates many many times before the individual is adult. However, a child conceived after mutagen exposure would either be unaffected, or have one side of their DNA entirely derived from a mutant cell in the parent’s gonads, and thus be entirely mutant. Does that make any sense? ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [August 2, 2008, 8:54pm UTC](https://boards.straightdope.com/t/heritability-of-a-physical-defect-caused-by-in-utero-environmental-poisoning/458621/3 "2008-08-02T20:54:39Z")
If the mutagen affected the cells that go on to form the gonads in the developing fetus, then it is possible that the mutation could be heritable. Also, there is the possibility of what are called [epigenetic](http://en.wikipedia.org/wiki/Epigenetic) changes. These are changes to DNA caused by external factors. These changes do not change the DNA sequences, but introduce changes to the DNA backbone, and interfere with gene expression. Some of these changes appear to be passed on to offspring, as discussed in a recent New Scientist [article](http://www.newscientist.com/channel/life/mg19926641.500-rewriting-darwin-the-new-nongenetic-inheritance.html). I have a subscription, so will add some quotes, but you may wish to see if you can get the article from a library. > [@](#): > > Now all that is changing. No one is arguing that Lamarck got everything right, but over the past decade it has become increasingly clear that environmental factors, such as diet or stress, can have biological consequences that are transmitted to offspring without a single change to gene sequences taking place. In fact, some biologists are already starting to consider this process as routine. > > … > > The implications for public health could also be immense. Some researchers are talking about a paradigm shift in understanding the causes of disease. For example, non-genetic inheritance might help explain the current obesity epidemic, or why there are family patterns for certain cancers and other disorders, but no discernible genetic cause. “It’s a whole new way of looking at the inheritance and causes of various diseases, including schizophrenia, bipolar disorder and diabetes, as well as cancer,” says Robyn Ward of the cancer research centre at the University of New South Wales in Sydney, Australia. > > … > > It is becoming increasingly apparent, though, that environmental factors can have a direct impact too, with potentially life-changing implications. The clearest example of this comes from honeybees. All female honeybees develop from genetically identical larvae, but those fed on royal jelly become fertile queens while the rest are doomed to life as sterile workers. In March this year, an Australian team led by Ryszard Maleszka at the Australian National University in Canberra showed that epigenetic mechanisms account for this. They used RNAi to silence a gene for DNA methyltransferase - an enzyme necessary for adding methyl groups to DNA - in honeybee larvae. Most of these larvae emerged as queens, without ever having tasted royal jelly (Science, DOI: 10.1126/science.1153069). > > … > > In people, too, there is evidence that environmental impacts on fathers and mothers can produce changes in their children. This has led some researchers to consider a startling possibility. Could the current epidemic of type II diabetes and obesity in developed countries be related to what our parents and our grandparents ate? It’s just a flavour from the article (not wanting to quote too much), but it seems clear that environmental factors influencing gene expression may have consequences for offspring (and possibly their offspring). Of course, it is New Scientist and they may be overstating the case, so YMMV. But it looks like some environmental impacts can influence future offspring. Si ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [August 3, 2008, 3:23am UTC](https://boards.straightdope.com/t/heritability-of-a-physical-defect-caused-by-in-utero-environmental-poisoning/458621/4 "2008-08-03T03:23:45Z")
Thank you!The responses were very informative. ---
**Author:** ![Cub\_Mistress](https://avatars.discourse-cdn.com/v4/letter/c/ea666f/32.png) [@Cub\_Mistress](https://boards.straightdope.com/u/Cub_Mistress)\ **Post date:** [August 3, 2008, 2:04pm UTC](https://boards.straightdope.com/t/heritability-of-a-physical-defect-caused-by-in-utero-environmental-poisoning/458621/5 "2008-08-03T14:04:16Z")
The thalidomide babies of the late 50’s/early 60’s have an rate of passing on the disabilities 5 times greater than the general population. [thalidomide](http://www.hazardcards.com/card.php?id=29) [another cite: PDF](http://www.who.int/lep/research/Thalidomide.pdf) ---
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [August 3, 2008, 5:22pm UTC](https://boards.straightdope.com/t/heritability-of-a-physical-defect-caused-by-in-utero-environmental-poisoning/458621/6 "2008-08-03T17:22:41Z")
Schizophrenia may be caused by an in-utero viral infection. [http://www.mentalhealthchannel.net/schizophrenia/causes.shtml](http://www.mentalhealthchannel.net/schizophrenia/causes.shtml)