'When Ancestry DNA revealed a family secret, I wished I'd never done the test.'

My husband and I had a long-running debate over who is more Viking. He claims that his size and strength must be down to ancient Norse blood running through his veins while I simply point out all the white blonde hair and blue eyes at my family gatherings.

Neither of us has ever had any indication that we might be right other than a stirring in our loins as we watched Ragnar and Lagertha do their thing on Vikings, so after a few meads at home we decided to jump online and order DNA testing kits to settle the argument once and for all.

The test was simple enough and when the results came back we found that our genealogy was remarkably similar. As we pored through the results with an awkward: "Sh*t, I hope we're not cousins" we finally stumbled on the Scandanavian blood, which we both had. Me more than him! Like the Shield Maiden, Lagertha, I am victorious.

Initially, there was a bit of activity around these test results. I received a couple of messages from DNA enthusiasts who had links with me and were trying to piece together what kind of second, third or fourth cousin I was as they built their family trees. But for me, the Viking news was what I really wanted out of it, so I turned off notifications and forgot about the site for a year or two.

Then some friends came over and the Viking debate reared its head again over a few drinks.

"Ha, I have proof!" I exclaimed as I ran to grab my laptop with the hope that I still had the logins saved. I did, and when I accessed the site I was met with a barrage of messages from a user desperate to talk to me. A user that matched as either a close cousin or a half-sibling on my dad's side of the family.

Watch: The signs you have a toxic sibling. Post continues after video.

From the outset, I had the gut feeling that this was going to be a Pandora's Box that I should just let lie. The messages came at a time when emotions were already on high for my family. My brave, beautiful mum was coming to the end of a years-long cancer battle and my dear stoic dad was the one nursing her through her last weeks at home.

After reading her messages and finding out her age, it was apparent that she might very well be my dad's child, born before he ever met my mum. I made the decision to reply to the woman's desperate messages, explaining that while I was excited to explore what this connection may be, I was asking for a period of grace as my family dealt with what was happening with my mum right now.

The reply was instant: "Of course. I don't want to interfere in anybody's family. I was adopted and I just want to know my medical background to know if there is any history of anything I need to be worried about."

I responded straight away, letting her know that we are a large and loving family and would be more than happy to figure this all out. In fact, this could be the happy news that our family needs, but if it could wait just a few weeks that would be so appreciated. I let her know that I had not told anybody yet, and I hoped she could understand.

Then I received Facebook and Instagram friend requests. And then the calls from my siblings asking who this person was that was sending them the same requests.

The cat was out of the bag. I told my siblings what had happened and they agreed that we should wait to tell our dad. We all accepted her requests and reiterated that we were keen to explore the connection and, again, requested a grace period as we navigated this awful time for our family.

Once more she responded that she only wanted her medical information, nothing more, and that she had no plans on disrupting our family.

To the best of our knowledge, we supplied any medical information that we knew from my dad's side of the family, thanking her for her patience with a promise to be in touch when the timing was better and asking that she not reach out to our dad just yet, please.

The woman responded by sending friend requests to anyone even remotely related to us on social media. Including our dad. In addition, she managed to track down my parent's home address, sending him a letter asking if he knew that she existed and did he ever think about her on her birthdays.

Dad's world was flipped. He had no idea that he had another child, but after reaching out to an ex-girlfriend's family it was confirmed that his former lover, now deceased, had a baby girl who was surrendered for adoption over 55 years ago.

Dad responded, letting her know that he was thrilled to have another child and was excited to get to know her. He also explained that he hoped she understood that, right now, he was in the midst of a very heartbreaking farewell to his wife of over 50 years, and that if his response was lacking at all, it was simply down to that.

Our new sister responded with a series of public Facebook posts announcing that was thrilled to have found her dad, tagging him, and in turn letting our entire extended family, including my mum's side of the family, know this story before any of us had time to process it, let alone tell anybody. The posts also announced that she had found siblings but that "we weren't being very nice" to her.

Mum and Dad were inundated with calls from family and friends.

In a time that should have been restful and reflective, they were thrown into chaos that could never have been imagined, including unannounced visits from my new sister who would turn up with bags packed, asking to stay over.

I was mad. My siblings were mad. This didn't have to be like this. The absolute lack of respect for my mum's last days had us in a rage. I blocked my new sister on all social media accounts.

She could have come into this treading gently, particularly given the circumstances. She could have chosen not to smash into our family like a raging bull. My not-so-Viking husband blamed the fallout on her "zigging when she should have zagged." I blamed it on her being a self-centred, disrespectful *****.

My mum passed and our secret sister continued her rampage of pushiness. While her words said that she only wanted medical information, her actions spoke of a much deeper need to have the unadulterated attention of our dad, who has barely been given the space to grieve his lost wife.

It's been a few years now and the only person in our family that she has a relationship with is our father. One by one, my siblings also cut contact with this woman after behaviours that can only be described as concerning.

Her take, according to the many public social media posts she makes, is that we are all jealous and never want to share our dad. Our response is to remain silent and let the trash take itself out.

The reality is that, for us, her existence will forever be tied to that awful time when we let our mum go and how that time was nothing like it should have been thanks to a bloody DNA test and a dumb fight about Vikings!

The author of this story is known to Mamamia but remained anonymous for privacy purposes.

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Feature image: Getty.