The science behind homosexuality is a topic that continues to vex scientists. But much more is known now than 10 years ago.
That was when Boston Globe magazine staff writer Neil Swidey wrote an acclaimed piece on the subject, pulling together then-cutting edge research showing homosexuality had a genetic origin. It became one of the most-read online pieces in the newspaper's history.
Skip ahead to 2015, and he's done a similar deep dive, talking to researchers to discover what new theories have emerged.
Swidey has found that sexual orientation, in general, is no longer seen as binary (straight/homosexual) but fluid, and that a complex interplay of genetics, the environment of the mother's womb and fraternal birth order all seem to play a part in determining whether an individual will be attracted to their own sex later in life.
To listen to the full interview, click on the blue audio player above