Do Fathers Matter?: What Science Is Telling Us About the Parent We've Overlooked by Paul Raeburn Read Free Book Online Page A

abnormally large yolk sacs. One had poorly organized brain tissue. Another had a beating heart, but no head.
    It was clear that fathers contributed something essential to the survival of developing embryos. No one had any idea what that essential contribution was, but Surani was determined to find out. Surani tried reversing the experiment: he produced fertilized eggs with two sets of fathers’ genes. Those embryos did not survive either. He knew his experimental technique was correct, because when he used the same equipment to combine fathers’ genes with mothers’ genes, the embryos survived. His conclusion was that mothers and fathers each contributed something with their genes that marked them as “paternal” or “maternal”—and that both were essential to the survival of the fertilized egg.
    He knew that “something” wasn’t in the genetic code itself, which is the same for mothers’ and fathers’ genes. A maternal hemoglobin gene is essentially indistinguishable from a paternal hemoglobin gene (although there are minor individual variations). The genes had to be marked in some way that didn’t alter the code. This was unexpected and difficult to accept at first. But it was an important new genetic phenomenon. The principal reason that Surani’s colleagues didn’t believe the finding was that the discovery violated the genetic principles known as Mendel’s laws, discovered by the German monk Gregor Mendel in the mid-nineteenth century. His work—which was lost for more than three decades before being rediscovered in 1900—forms the bedrock upon which modern genetics was built. Mendel painstakingly bred pea plants for eight years to see how different traits were passed from one generation to the next. He bred tall plants with short plants, green peas with yellow peas, and so on, to see what would emerge in the offspring. The results were entirely unexpected and groundbreaking.
    Before Mendel, biologists thought that crossing two different plants would produce something of a mix: crossing a plant with wrinkled seeds with another that had smooth seeds would produce plants with slightly wrinkled seeds. But that wasn’t the case. Some plants had smooth seeds, and some had wrinkled seeds, depending on which way Mendel crossbred the plants. There was no in-between. These characteristics arrived in the next generation as discrete traits; they did not blend with each other. The traits were associated with genes that are passed from each parent to offspring and that do not blend with each other. Mendel could not know that; genes had not yet been discovered. He knew only what he saw in his pea plants.
    To Mendel, whether a trait came from a mother or father made no difference. Genes combined in certain predictable ways no matter where they originated. Surani’s work posed a direct challenge to this principle. Scientists had to decide whom they were going to believe—Mendel or Surani. That was no contest. Most scientists concluded that if Surani’s work violated Mendel’s principles, Surani was wrong. “Around 1983, people in Cambridge were starting to hear about these strange experiments, and I was invited to give a seminar in the department of genetics. I could see they were very skeptical,” he recalled. “But I was convinced.” He soon got some help from another researcher in the United States—Davor Solter, then at the Wistar Institute, an independent biomedical research center in Philadelphia. It so happened that Solter had been doing similar experiments, and he was coming up with the same findings. This was crucial: controversial results such as these are harder to dismiss when they’re found independently in more than one laboratory.
    In one of his early publications, Surani called these maternally or paternally marked genes “imprinted genes,” as if they were stamped with an identifier saying they came from mother or father. The name stuck. Further research showed that most human genes are