Neil Patrick Harris had suspicions on which is his biological twin despite not wanting to know

Neil Patrick Harris said he has suspicions about which of his twins is biologically his, however, he has 'no interest' in ever finding out.

Harris, 51, and his husband David Burke, 49, became parents to twins Gideon and Harper - who are 13 years old - after a surrogate carried and gave birth to them in 2010.

Harris and Burtka first met in 2004 and after becoming friends, they went public with their relationship in 2007.

Neil Patrick Harris and David Burtka with their children, Harper and Gideon (Instagram/@nph)

They later welcomed their twins in 2010 before getting married in Italy in 2014.

The children are non-identical, as two separate eggs were used.

They each donated sperm in the hopes that either would fertilise the egg, but to their surprise, the twins were conceived.

Speaking to American broadcaster and journalist Barbara Walters in 2014, Harris explained: "We inserted one of my sperm and one of David's sperm into two eggs with the hope that they would both take, just because we both wanted to be dads biologically. Both took, miraculously."

Harris also explained that he has no interest in finding out which of his twins are his biologically.

He explained: "I have no interest in [finding out]. We are their parents and I love them implicitly."

While the couple have no idea about who the biological father is for each of their children, Harris said that they have suspicions 'based on their behaviour'.

However, the How I Met Your Mother star did not reveal what those suspicions were, nor what child he thought could be his biologically.

Harris recently offered a glimpse into family life, explaining that his daughter, Harper, is 'unfazed' by horror films, but did end up staying in his bed for four nights after watching The Shining.

Speaking on The Tonight Show Starring Jimmy Fallon in 2022, Harris said: “What do you say to a girl who wants to watch horror movies?

Neil and David are the biological parents of the twins (Sonia Moskowitz/Getty Images)

“Do you say ‘Absolutely not’ because then she wants to watch them more?

“She just kept asking and persisting, and so we watched The Shining last week.

“I don’t know if it was a good call."

Speaking about her reaction to the movie, he added: “I said, ‘So what did you think?’ And she said, ‘I’m mildly disappointed.'

“She has slept in our bed for, like, the last four nights.”

The dad-of-two recently shared an adorable photo of his family on Instagram, while celebrating Father's Day.

In tribute to his husband, he said: "David, you’re the most amazing father I know. Thanks for your dedication and commitment to parenting our children. They are made better because of you. Happy Father’s Day!"

Alongside the heartfelt words was a photo of David with the twins and their dogs.