Nowadays we know that our genes and the environment we live in, in constant interaction, are what make us what we are. Along history, however, much harm has been caused in the name of science by well-meaning ignorants and pseudoscientists who either didn't know or chose to ignore this fact. Eugenics, Social Darwinism and even Communism (which resulted in the most monstrous social experiments ever conducted) are some examples of the possible consequences of attributing human behavior either to genes or to environment alone. Unfortunately, pseudoscience and ignorance still abound and help sustaining myths, prejudices, racism, homophobia, among many other evils.
Outside the realm of science too, there have always been those who try to attribute much of what we do/are to supernatural causes (temptation, demon possession, witchcraft, etc). Witch-hunts, discrimination, obscurantism and religious extremism are good examples of the possible consequences.
Fighting ignorance and established prejudices is never easy. When Edward O. Wilson, after two decades observing animal behavior in the wild, published a book called “Sociobiology”, in which he tried to explain the origins of social behavior, he didn't imagine the furious reaction he was going to provoke. The problem was that the human species was also object of his analysis.
The video below is about Mr. Wilson and his work, which includes environmental activism. It is a little bit long, but it is worth taking the time to watch it.