It makes me wonder if these people were absent from school when basic biology was taught? Perhaps these basic facts were never taught. Perhaps there is an agenda on the part of the education system to keep people uninformed and ignorant of the basic facts of life.
Fertilization is the fusing of the gametes, that is a sperm cell and an ovum (egg cell), to form a zygote. At this point, the zygote is genetically unique from either of its parents. Many members of the medical community accept fertilization as the point at which life begins. Dr. Bradley M. Patten from the University of Michigan wrote in Human Embryology that the union of the sperm and the ovum "initiates the life of a new individual" beginning "a new individual life history." In the standard college text book Psychology and Life, Dr. Floyd L. Ruch wrote "At the time of conception, two living germ cells—the sperm from the father and the egg, or ovum, from the mother—unite to produce a new individual." Dr. Herbert Ratner wrote that "It is now of unquestionable certainty that a human being comes into existence precisely at the moment when the sperm combines with the egg." This certain knowledge, Ratner says, comes from the study of genetics. At fertilization, all of the genetic characteristics, such as the color of the eyes, "are laid down determinatively." James C. G. Conniff noted the prevalence of the above views in a study published by the New York Times Magazine in which he wrote, "At that moment conception takes place and, scientists generally agree, a new life begins—silent, secret, unknown."^ Rice, Charles (1969). The Vanishing Right to Live. Garden City, NY: Doubleday & Company, Inc. pp. 29–31.
If someone is supporting their pro-choice viewpoint by denying scientific facts, their argument is extremely weak. It would be better to simply state that they are pro-choice despite any biological facts that exist. They are then in the realm of claiming a fetus may be a human being, but they will deny it personhood - and that is a philosophical argument, not a scientific one.
It is a biological fact that species produce according to their own kind; in other words, dogs have puppies, cats have kittens, horses have foals, and humans have human babies. What else could the fetus in the womb be except a human being?
As for the presence of genetic material, one commentator pooh-poohed the idea that the colour of the baby's eyes were determined at fertilization, that its sex was determined, that the shape of its nose was determined. The study of genetics has already established that the egg contributes 23 chromosomes from the mother, the sperm contributes 23 chromosomes from the father and this means the fertilized egg has 46 chromosomes which determine every genetic trait for that being.
Also a very basic reading of any article on in-vitro fertilization dispels the claim that life does not begin with fertilization. People who are using in vitro fertilization to get pregnant know very well that the implanted fertilized egg is already their baby, that may or may not survive within the womb. They would certainly never agree to have unfertilized eggs implanted; that would be entirely useless. And of course the world of in vitro fertilization raises the moral problem that many pro-lifers have with it: what to do with all those frozen embryos that have been created and are not being implanted in a uterus to come to term and be born?
The Catholic Church would have no problem with in vitro fertilization if those fertilized eggs were not human beings.
So if you are pro-choice and are using biology to back up your position, please do us all the favour of getting informed and educating yourself about these things. Simply shouting at pro-lifers that they have the facts wrong will only damage yourself in the long run, as your argument is based on untruth.
One does not have to be religious to be pro-life; in fact, many pro-life advocates were people who were convinced by the science of reproduction. Bernard Nathanson, one of the founders of the abortion group NARAL, was just one of those such people. It was his study of fetology with the invention of ultrasound that made him change his position of being completely pro-abortion to being completely pro-life.