When Neil Patrick Harris and his husband, David Burtka, became parents in 2010, the men decided that they didn't want to know the biological father for each of their twins.
Four years later, Neil told Barbara Walters that he still has 'no interest' in learning which twin is his biological child.
The 41-year-old actor explained exactly why that was during Barbara's 10 Most Fascinating People Of 2014 special on Sunday.
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Fascinating: Neil Patrick Harris, 40, made Barbara Walters' list of the 10 Most Fascinating People Of 2014 and joined her for an interview on Sunday
'I have no interest in [finding out]. We are their parents and I love them implicitly,' Neil explained on the subject of paternity.
The children, Gideon and Harper, were born via a surrogate from eggs fertilised by sperm donated by Neil and David, 39.
'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,' Neil said of the babies' conception.
'Both took, miraculously,' he added.
No interest: Neil explained that he and David Burtka had 'no interest' in learning the genetic father of each of their two children, Gideon and Harper
Happy couple: Although together for many years, Neil and David did not marry until 2014, wanting to wait until gay marriage was legalized
Despite having no need to know the genetic father of each of the children, Neil did admit that the parents have suspicions 'based on their behaviour.'
Neil made Barbara's 2014 list for a host of reasons, including his Tony win for the lead role in Hedwig And The Angry Inch.
He also concluded his long-running sitcom, How I Met Your Mother, in the spring and has long been a well-known figure in the acting world.
The list: Others named as fascinating by Barbara included Amal Clooney, Taylor Swift, Scarlett Johansson, Oprah Winfrey, and more
Big year: In addition to his marriage, Neil concluded his How I Met Your Mother role and won a Tony award for Hedwig And The Angry Inch
Fatherly love: 'I love them both implicitly' was Neil's reason for not needing to know the biological father of his children
Suspicions: Neil did admit that he and David have suspicions about the twins' paternity, based on behaviours
A breakout star and young teen idol after the premiere of Doogie Howser, M.D. in 1989, Neil kept his TV, film, and stage career strong well into adulthood.
And his personal life became international news in 2006 when Neil publicly announced that he was 'a very content gay man.'
Although Neil was privately engaged to David at that time, the two didn't get married until 2014, wanting to wait until their union would be legal.
The other nine figures on Barbara Walters' Fascinating list were Amal Clooney (formerly Alamuddin), Oprah Winfrey, Elon Musk, George R.R. Martin, Chelsea Handler, Scarlett Johansson, Taylor Swift, Michael Strahan and David Koch.
Child star: Neil got his first big break in 1989, when he began starring in Doogie Howser, M.D.
Teen idol: Quickly embraced as a heartthrob, Neil appeared alongside Johnny Depp, Kirk Cameron, and other young stars
Big news: In 2006, Neil came out publicly as gay, one of Hollywood's first leading men to do so
Playing against character: Neil had already begun to play Barney Stinson, a serial womanizer, on How I Met Your Mother when he came out
New highlight: While a long-time theatre veteran, Neil received his first Tony award - at a show he hosted - in 2014
