After meeting on an online dating site, the pair spent two years talking before finally meeting.

But when Lee took Paul home to meet his family, they remarked how similar he looked to his mother's ex-husband Ron. 

After discovering Paul shared a last night with Ron, mother Ena revealed that she did have another son but gave him up for adoption when he was a year old.

After having a DNA test, Jeremy said: "You are having a physical sexual relationship with a man that you love and want to marry and at some point somebody might tell you that he could be your half-brother."

Lee replied: "It makes me sick. It makes me basically horrible. I can’t describe it."

The host then revealed that the pair, who had previously decided they would one day get married, did share the same mum.

After going in to shock, the pair was offered counselling by the show's Graham.

The segment was originally aired in 2012 but was repeated as part of the 10 year anniversary.

Jeremy revealed that he's since caught up with the pair who have both moved on from their relationship but are closer than ever as brothers.