Is your genetic code fixed at birth?

Or can it change due to environmental factors as you go through life? I’m referring to the genetic code that you pass on to your offspring through breeding (i.e. It is my understanding that one of your risk factors for certain diseases, such as heart disease, is heredity (it’s “in your genes”). Can the risk factor you are going to pass along to your children be increased or decreased due to enviornmental stimuli you experience post-natal, especially if experienced during those early stages of development when your body is changing rapidly?)

Please note that I am not a doctor, nor a scientist. My basic assumptions may be wildly mistaken, so please correct any fallacies I may have stated or implied.

Your DNA is, basically, fixed.

Changes result, as I recall from science programs, in cancer.

Your genetic code is fixed, and can’t be changed except by “accident” (chemical or radiological damage).

You genetic code can change only through mutation or changes that occur as a result of the environment. These can include exposure to radiation (sunlight) or chemicals (cig smoke).
These changes to your DNA can only be passed on to your offspring if they occur within the DNA of sperm or egg. If sure that other experts will speak to this.

No. A mutation can cause trouble in some cases, and not cause any trouble at all in others. The trouble doesn’t have to be cancer related either. As others have said, the change can caused by the environment, or a copying error.

There are cases of (apparently new) germ line (egg and sperm) mutations that can cause trouble in the offspring.

You genetic code is generally fixed, but changes quite a bit. Damage from mutagenic agents, errors during replication, insertions from viruses, even the odd transposable element that jumps from one part of the genome to the other. These can lead to the death of the cell they occur in, can contribute to the cell becoming cancerous, or may do nothing at all. By the time you’re born, a mutation in your somatic cells (that is, everything except eggs and sperm) is very unlikely to do much else. A few mutant cells, unless they start reproducing uncontrollably, simply won’t be noticed under all the normal ones.

Mutations can be passed down to your offspring. That’s what evolution is. This occurs when the mutation is in your germ line. When producing germ cells, your matching chromosomes swap some DNA between pairs, so that your offspring don’t get precisely the same chromosomes you have (exception being the X and Y in males). This can produce new novel mutations, especially when the swap isn’t precisely even.

I know I’ve read stories about areas where a large cluster of kids were born with the same genetic problem. Can’t think of the particulars off hand but someone else might be able to.

in mean in utero exposure? (cig smoke, drugs, caffeine)

No, it’s fixed at conception, approximately 9 months earlier than birth.

It guides the development of the fetus over those 9 months, and various factors can interfere with that development.

After birth, various factors (exposure to radiation, harmful chemicals, smoking, etc.) can cause mutations in the genetic code material in various cells of your body. Most go unnoticed (there are a lot of cells in the body), some cause diseases. But only in the rare case where they affect the reproductive cells (testes or ovary) do they change the genetic code that you pass on to your children.

It’s possible. That’s why pregnant women should not get X rayed in the baby area. More likely the exposure was with the sperm or egg which could have been years before conception.
BTW, I don’t believe that caffeine causes mutations.

There is also Epigenetics.

Even with identical twins (same genetic code), the epigenome can turn off some genes and result with different results.


Assuming something similar to this is true, it’s not because of mutations in their parents; a mutagen will pretty much randomly screw up DNA, and will cause different mutations in different cells.

The best explanations for such a cluster would be:

  1. It’s not a genetic problem, but a developmental problem, due to being exposed to something in utero or during early childhood. It’s quite possible that a group of pregnant women could be exposed to the same chemical (e.g. Thalidomide, mercury) that would cause similar problems in their developing fetuses. The key is that a chemical that causes developmental problems can have a similar effect in different individuals.

  2. The kids are all to some degree related (they’re all from the same somewhat inbred group), and happen to all inherit the same genetic defect from their parents, who got it from a common ancestor. Hemophilia in the European Royal families is an example; the common ancestor that originated the defect is known, but it was passed on to many individuals often separated by several generations from the original.

**N91WP ** beat me to it. One’s epigenome might turn out to be the biggest discovery for genetics since Crick and Watson. The fact that the processes of ones code can be manipulated really opens up possiblilities that are not only effective, but extremely simple and can be done under existing technology.

This bears repeating as I do not believe it comes out clear in most of the other posts. While people are talking about the genetic code of individual cells (or clusters of cells particularly in the case of cancer) changing, your overall genetic code will not. No Star Trek style wacky whole body mutations.

The study I was looking for was about aneuploidy caused by pollution. All the initial reports I’ve found have been debunked though, so apparently there was another explanation.

Someone correct me if I’m wrong, but I’ve heard that the older you are, the more likely you are to produce eggs or sperm with a mutation.

And this may be a slight highjack, but there have been y chromosomes found in the blood of women who have given birth to boys, sometimes years later. So you can pick up and carry genetic material that you didn’t have when you were born, but in this case it will just ride passively without any noticable effect. (They went looking for the y chromosomes because they’d be easy to find. They’re assumed to be evidence that other chromosomes are also passed. Looking for them would be murder, though.)

Television has taught me at least two ways to change your genetic code:

  1. exposure to focused gamma rays, causing you to turn green and grow in size when angered;

  2. getting a fly trapped in your matter transporter, causing your DNA to be combined with the fly’s and you to be turned into a man/fly hybrid.

Independent from mutations caused by radiation, chemicals, etc., it is NOT the case that one’s genes are fixed.

In particular, the genes of the immune system undergo somatic (hyper)mutation. Tonegawa won the Nobel prize for discovering this.

Once again, though, we are talking about individual cells, not the whole body.


Not quite correct.

If there’s a fly trapped in your matter transporter then what comes out the other end is you with a fly’s head and a fly with your head.

That’s two man/fly hybrids.