It's been a popular porn category for years, but one set of US step-siblings say they've taken their romance to real life.
Diana Camila Avila and Jordie Vena have hundreds of thousands of followers on TikTok, on their joint account 'alphafamilia'.
In their videos, the Canadian step-siblings document their relationship, which they say they've kept secret from their parents since they first started dating six years ago.
Instead they post videos trying TikTok trends, or giving insights into the early days of dating with eyebrow-raising videos like: "How the first kiss with my stepbrother went".
Speaking to LadBible, Avila said it was 'love at first sight' but they initially kept their feelings from each other because of the unusual circumstances.
Now they've gone public, she says they "get negativity daily".
"It's hard for people to understand our relationship, but love is love. It's hard to know who you're going to fall in love with," she added.
The backlash is indeed evident in the comments on their videos. "Please tell me you're not actually step-siblings," and "this is disgusting," are regular refrains.
"'I'm going to ask TikTok to remove the video so you can't hurt anyone else with this," another person recently commented.
Others have lept to their defence.
"Having your step sibling as your partner isn't as uncommon as you think - they're not blood related so what's the big deal?" defended one follower.
But of course, in this age of social media, it has to be questioned whether the pair are actually step siblings - or even are in a relationship - or if they've seized onto a goldmine of likes and followers.