Lorde's teenage sister Indy Yelich-O'Connor has come out as bisexual on social media.

The New York-based teenager posted on Twitter and Instagram today saying: "Plot twist (I like boys and girls)."

Social media users sent Yelich numerous messages of encouragement and support.

"Proud of you! Hopefully one day we'll live in a world where this won't be considered a plot twist," a Twitter user said.


"And after the plot twist there's a happy ending because we love and support you all the way, no matter what and I happen to be gay so today's going to be a good day!! Indy you're amazing, never doubt love," another user said.

Yelich, who recently released a book of poetry called Sticky Notes, has thanked followers for the support.

"I had so many messages of support and the sun was shining, and I just love New York. So grateful for my life and all the people in it," she wrote.