While the public may be wondering which one of their dads Gideon and Harper takes after, Neil Patrick Harris and his partner David Burtka aren’t concerned.

“I have no interest in [finding out]. We are their parents and I love them implicitly,” the actor told Barbara Walters in her_ 10 Most Fascinating People Of 2014_ special.

The now four-year-old twins Harper and Gideon were born via surrogate, whose eggs were fertilized with one sperm from Harris and one sperm from Burtka. “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,” Harris said. “Both took, miraculously.”

That means NPH is biologically the father of one twin while Burtka is the biological father of the other. But the couple don’t plan on ever digging deeper into paternity, though Harris indicated that they do have some suspicions based on their kids’ behavior.

NPH and David join some pretty other big names on the list of those who’ve used a surrogate. Jimmy Fallon and wife Nancy Juvonen just welcomed their second daughter, Frances, via surrogate. And Grey’s Anatomy’s Ellen Pompeo surprised us all when she announced she had a second child via surrogate two months after the actual birth. (via Daily Mail)