According to the article, there are 47% of Americans believe people are born gay, 33% believe homosexuality is due to external factors.

     The researcher asked a random sampling of 1535 Americans over the age of 18, only 13% of Americans said homosexuals are born gay, and 56% of Americans think it is due to upbringing and environmental factors.

     After 1977, the number of people who believe sexual orientation is determined at birth has increased.
   
     In 2011, 40% of Americans believed homosexuals were born gay, and 42% believed homosexuals were products of their environment.

     Frederick L. Whitam, who is professor in Arizona State University, think homosexual orientation is biologically based but that sexual orientation itself is also biologically derived.

    However, A. Dean Byrd, Clinical Professor of Medicine at the University of Utah, says:"The scientific attempts to demonstrate that homosexual attraction is biologically determined have failed. The major researchers now prominent in the scientific arena--themselves gay activists--have in fact arrived at such conclusions. There is no support in the scientific research for the conclusion that homosexuality is biologically determined."

     According to Gallup, more American subgroups believe that sexuality is determined at birth.Researchers estimate that approximately 1-10% of the US population is lesbian, gay or bisexual.

Sources:

ProCon.org May 30,2013