What is homosexual? So, let’s start with Start with research that suggests that homosexuality is caused. Genetic over parenting in 1991 by Dr. Richard Old. And Michael homosexual behavior was studied in male twins. Found that in identical twins or twin with identical chromosomes. If one is gay more people are likely to be gay to 50 percent, while the twin like. Twin or a different chromosome. Are likely to be gay, only 20 percent by the twins of different kinds have been raised as well. Whether it's food what experience and the practice of parents