Viewers took to Twitter to express their fears!

Hit soap Eastenders is never one to shy away from controversial story lines. But the latest plot twist may be its most daring one yet.

Courtney Mitchell’s return to Albert Square earlier this month alongside her dad Grant, was one of the soap’s most anticipated moments. But what began as a moment of excitement, quickly turned to one of fear.

When Mark Fowler junior also landed in the Square, following a call from Phil, fans began to piece together a shocking soap scenario. Mark is unaware that Grant is his father. Courtney is also unaware that her half-brother is so close by.

Eastenders

The siblings met for the first time last weekend, and Eastenders’ fans are worried that the two will become close. So close, in fact, that their new friendship may turn into incest.

Eastenders

And their first meeting wasn’t the only sign of a potentially incestuous romance developing between the pair. The siblings also locked eyes at Shakil Kazemi’s 16th birthday party. As a game of ‘truth or dare’ got underway, Courtney pressed Mark on whether or not he fancied her.

Eastenders

Viewers’ shock!

Viewers took to Twitter to raise their concerns, reacting to the fact that Mark appeared to flirt with Courtney.

One viewer commented: “Aw Courtney Mitchell’s gonna get with her brother isn’t she,” and another said: “Easy there Mark, that’s your sister, bruh!”

Another added: “Mark and Courtney are so going to get together, and then realise there half brother and sister!”

And the raised eyebrows continued with these comments…

“Courtney and Mark better not hook up, otherwise it’ll be incest” said one. While another said: “The writers better not think about doing what I think they might do.”

Mark is the product of an affair between Grant and Michelle Fowler. Grant only discovered that he had unwittingly added to his brood when he found a letter in ex-wife Sharon’s handbag.

Will an incest plot be taking things too far for the soap? Join the conversation on our Facebook page.