(CNN) — Genes cannot be used to predict who will be gay or straight, according to a new study published in Science Magazine.
A team of international researchers analyzed data for more than 477,000 people in the United Kingdom and the United States.
The researchers found same-sex attraction appears to run in families, and identical twins are more likely to be aligned in their sexuality.
The study also said several hundred genes appeared to have an influence on sexuality.
Researchers said while sexual orientation cannot be predicted by a single gene, environmental factors play a big role.