I’ve just found out my partner and I have same dad – and we are both in shock

DEAR DEIDRE: I’VE just found out that my partner and I have the same dad – and we are both in shock.

We’ve been together for two years. He is 29 and I’m 27.

I’m an only child. My mum got pregnant after a one-night stand.

I’ve never known my father but mum said she had “double the love” for me so I didn’t need a dad. I’ve always been close to my grandfather and that was enough for me.

I met my partner on an evening out and we had sex on the first night.

I thought that it would be a one-off. But he called me the next day and said he’d love to see me again. We started dating and moved in together after eight months.

Last year my partner’s brother bought him a DNA kit for fun.

The results came back and he found some previously unknown distant cousins, who had also registered.

When it was my birthday, my partner bought a kit for me. I was full of trepidation, knowing that my father was out there and could have other kids.

But I was horrified to find that my half-sibling was my partner.

I’ve met “his” dad once at a wedding. He divorced my partner’s mum and has now remarried. He’s a nice guy and lives in Spain.

My partner and I have been left reeling by this. We don’t know what to do with the information.

Could the genealogy company have got it wrong?

Can we say nothing about our relationship and continue as we are — and what if we want children ourselves one day?

DEIDRE SAYS: It would be good to establish the validity of these results.

Unfortunately, many who take these DNA tests because they are curious about family origins are not prepared for the emotional fallout when previously unknown relatives are identified.

You can contact cellmark.co.uk (0800 036 2522), which provides approved DNA testing, for guidance.

If the tests are correct, then I’m so sorry but continuing to have this relationship would be incestuous.

I know you must be devastated but you will need to break up. What drew you together was most likely the family traits you share, which is known as genetic sexual attraction.

Talk it all through with a counsellor.

My support pack How Counselling Can Help explains where to find a reputable therapist.