Let’s puzzle together over two questions. Will my bad habits before my children are conceived affect them after they are born, and will these bad habits continue to negatively affect my grandchildren and possibly even my great-grandchildren? The second question is this: Does science, our amazing enterprise for discovering the facts of nature, ever have to change its mind?
I’ll begin with my bad habits before my children are conceived. I used to wonder what Exodus 20:5 meant when it said that children will be punished for the sins of their fathers to the third and fourth generation. Is that fair? Then a few years ago, an article appeared in the prestigious scientific journal Nature, titled “Epigenetics: The Sins of the Father.” Are scientists discovering that the Bible really does know what it’s talking about? In this case, the answer seems to be yes, although most scientists probably won’t credit the Bible for that hint.
For a number of decades, it has been known that our genes determine what we are. They define the color of our eyes, the shape of our noses, and how our stomachs and lungs work, and they influence how healthy we are. We can call genes our instruction manual, and during our lifetime, they apparently don’t change, although any mutations that we pass on to our children—what’s called “evolutionary change”—will affect what they will be like.
However, mutations are not the only way we can pass on genetic changes to our children and grandchildren. Another method of heritage change is called “epigenetics,” which means above the genes or outside of the genes. The epigenetic system puts tiny chemical tags on specific genes. These tags are like switches, and they turn genes on or off or modify their effects, and somehow these tags can also be passed on to our children, often for more than one generation. There are millions of these little tags in a single cell. It seems that epigenetic tags based on the behavioral information from father mice are passed on to their offspring. This is a radical new discovery!
Epigenetics is the study of these inheritable traits, the chemical tags that are not the result of a change in the genetic information. These inheritable changes are not mutations. They do not change the genes. They change the instructions for how the genes interpret the information within them. The awesome mechanism inside a cell decides how to use its genetic information!
hard drives and operating systems
Computers will illustrate what I’m talking about. Inside a computer is a hard drive that can hold a library of information. We use that hard drive to hold all the files we are working on. That hard drive is like the genes in our chromosomes, which also hold a large library of information. But if you unhook the hard drive from the rest of the computer, the files it contains can’t do anything because they don’t have access to the operating system with instructions that tell it how to use that information.
For a long time, scientists, even geneticists, thought that our genes directly control what we are and how our bodies work. However, the discovery of epigenetics has revealed that our genes need an operating system to tell them what to do. Our genes contain an enormous amount of information, but by themselves, they are like a hard drive that’s unhooked from the computer’s operating system. They can do nothing at all!
Scientists are now beginning to understand what this operating system is and how it works. Notice that I said, “Beginning to understand.” There is so much more to learn, but there has been a beginning.
The article in Nature that I mentioned earlier gives an example of epigenetic changes that are passed on from parents to their children, grandchildren, and great-grandchildren. Scientists exposed male mice to the gentle odor of peach blossoms, which the mice enjoyed, but each time they smelled the odor, the scientist gave them a mild shock on their feet. This happened a few times a day for several days. But after those few days, these mice reacted very negatively to that odor, even without their feet being shocked.
Then these male mice were mated with female mice that had never had that negative experience. We would expect that the experiences of the fathers would have no influence on their offspring. We were wrong! When the offspring were physically mature, if they smelled the odor of peach blossoms with no shock, they experienced the same negative response to the odor that their fathers did, and this effect lasted for several generations!
Yet, there was no change in the genetic structure of the genes in these parent mice to influence their response to the odor of peach blossoms in their offspring, which would have been an evolutionary change that would have taken many years and many generations of mice to bring about.
These mice experienced what God said in the second commandment: “I, the Lord your God, am a jealous God, visiting the iniquity of the fathers upon the children to the third and fourth generations” (Exodus 20:5, NKJV*). Somehow the negative reaction to a gentle odor—the sins of the fathers—was passed down from generation to generation. And this was not the result of a change in the structure of the mice’s genes, which would have been an evolutionary change.
Traditional evolutionary change occurs through mutations in the genes that do not exist in the parent but occur in their offspring. And minor mutations occurring one after another over many generations can bring about significant changes in future generations. This is how traditional evolutionary changes work, but it’s a long, drawn-out process that takes many generations to bring about. However, as we’ve seen in the experiments with peach blossom odors and shocks to the feet of male mice, significant change can be brought about in just one generation.
Now come back to that article “Epigenetics: The Sins of the Father.” From the time of Darwin until recently, it was believed that the experiences we have during our lifetime cannot be inherited by our children. They have to learn everything for themselves. This sounds logical, but hang on! The experiment with mice and the odor of peach blossoms demonstrates that our experiences during the years that we are alive can affect our children. This is one example of what epigenetics is all about. How we live sends epigenetic information to our children.
This was studied during the Second World War. The Nazis tried during several winter months to starve out the uncooperative people in a part of the Netherlands. This starvation experience affected the children of women who were pregnant during that time. If the difficult months came early during the pregnancy, the maturing children had increased rates of coronary heart disease and obesity. If those months of famine came late during the pregnancy, the negative results were different. Exposure to famine during pregnancy also resulted in children being born, who, when they became adults, had a higher incidence of schizophrenia. These were not mutations but epigenetic effects brought about by those little epigenetic tags.
Just as Exodus 20 implies, how we live our lives can affect the quality of life of our children and grandchildren. God does not punish the children for their parents’ mistakes, but the parents’ mistakes do influence their descendants. Such lifestyle factors as diet, smoking, stress, exercise, and exposure to pollution influence the epigenetic tags of both us and our offspring.
The good news is that these epigenetic tags don’t just produce negative effects. Some epigenetic processes are very essential. For example, all the cells in our bodies have the same genetic information, but different cells have very different functions. Muscle cells, nerve cells, and skin cells have the same genes—so why are they so different from each other? This apparently is the result of the epigenetic tags that manage the cells as the embryo develops, telling each type of cell how to use its genes, which proteins to make, and when and how much. Without that management system, we would all die.
I believe God created the epigenetic system to facilitate the beneficial adaptations of organisms to their environment. But we now live in a dangerous world, and consequently, some epigenetic modifications can have unfortunate results. The good news is that epigenetic changes can be at least partially reversed.
For example, if a heavy smoker stops smoking, the epigenetic damage from smoking during that smoker’s lifetime can be reduced. It also seems that if my unfortunate lifestyle harms my children, future generations with improved lifestyles can help to reverse this trend.
There are a number of other fascinating epigenetic effects in the animal and plant world. I will share two of them with you.
Blind cave fish. We were often told that blind cave fish became blind because of mutations that damaged the genes in their eyes. However, since they lived in darkness, the loss of eyes was not a disadvantage. Now it’s known that blind cave fish have normal eye genes. Their eyes have not been damaged by mutations. But since the fish live in darkness, epigenetics has turned off the eye genes, and the developing eyes in the embryo don’t mature and become functional. Presumably, if these blind fish were to change to life in an environment where there is light, epigenetics would eventually reactivate their eye genes so that they could see.
Dog breeds. There are more than two hundred breeds of dogs. Abundant evidence indicates that this is not evolution that results from mutations. Some mutations are involved, but it seems that most of this variation is epigenetic. At least 200 breeds were produced by selective breeding in about the last two centuries. That rapid and radical change cannot be the result of regular evolution. Evolution can’t possibly happen that fast, even if it is just microevolution. The genetic and epigenetic potential for such variation in shape and size had to be there from the beginning. I suggest that the Creator made the dog family with domestic dogs in mind to provide for human needs for protection, companionship, and other types of assistance that dogs can give so well.
Charles Darwin and his colleagues during the 1800s lived nearly a century before the discovery of genes and chromosomes. They believed that random changes of some kind, followed by natural selection, could gradually evolve new types of animals. Those changes had to be random since changes happening because they are beneficial would be evidence of intelligent planning. Darwin’s theory does not allow for any intelligent design or planning in nature.
But now, it seems that epigenetics does result in inheritable changes occurring because they are beneficial. God did have a hand in designing living things and giving them the needed mechanism to change.
So in answer to the second question I raised at the beginning of this article, scientists have had to revise their thinking—change their minds, if you please—to recognize that genes need a management system to tell them how to use the instructions they contain, and also that our genetic/epigenetic system can cause beneficial changes to occur that are not the result of evolutionary mutations.
Science often does have to change its mind. And my habits, both the good ones and the bad ones, will influence the lives of my children and grandchildren. It truly is a good idea to follow healthy advice and think about the future of our children and grandchildren as well as our own!
* Bible texts marked NKJV are from the New King James Version®.
Leonard Brand is a professor of biology and paleontology at Loma Linda University in Loma Linda, California, and he was chair of the Department of Earth and Biology Sciences for 33 years. He has been active in research and publishing during his career at LLU. He lives in Loma Linda with his wife, Kim.