A Gallup poll last week showed that 47% of people in the U.S. understand sexual orientation as something you are born with: Graphic by Chris Ritter for BuzzFeed In 1978, that number was only 13%. Broken down by other factors: Graphic by Chris Ritter for BuzzFeed The poll, taken in early May, also finds: shutterstock shutterstock shutterstock From 1986-1988, only about 1/3 of Americans thought gay and lesbian relations should be legal. As the "nature vs nurture" debate continues, scientists are working to pin-point what factors influence sexuality by working with other animals: Uriel Sinai / Getty Images A study published last month attempted to alter female mice sexual preference using serotonin levels. Researchers, led by Shasha Zhang at Peking University in Beijing, bred a group of female mice that lacked serotonin or certain neurons that release serotonin in parts of their brains. The results showed that these altered female mice preferred other females for sexual activity over males when given the choice. You can read the full report as published here. Researchers concluded that the survey demonstrates, "that a genetic manipulation reverses sexual preference without involving sex hormones." pnas.org From the results of the study: According to Yale Scientific, there are currently over 450 different animal species worldwide with documented homosexual behavior. Mathieu Belanger / Reuters As American public interest and acceptance increases on the subject, more scientists are getting involved in this type of genetic research. aglbical.org We may one day have a solid answer on the age old question of whether people are actually, "born that way."