They decided not to find out which one of them is the biological father of each of their twins.
This means a different woman carried the babies for Neil and David until they were born.

The couple has been very open about how they went through the process to have their children.
He said to her: “I have no interest in [finding out].
Explaining how they used a surrogate, he added: “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.
Since Gideon and Harper are fraternal twins and not identical, this means two embryos were involved—one for each twin.

A surrogate carried them, and the egg donor remained anonymous throughout the process, so Neil and David don’t know who she is.
Even though Neil and David don’t know which one of them is the biological father of each child, Neil mentioned to Barbara that they have some guesses based on the kids’ behavior.
Neil and his family made headlines last year when they showed their retro-style holiday cards in a partnership with Minted.
There was also “an additional shot of the family dogs on the backside of the card.”

Fans loved the card and quickly commented on it.
A third added: “You two are so creative!
Neil also posted a special message for the twins on Instagram on their birthdays in October last year.
“Happy birthday, Harper and Gideon.

“You are the lights of my life.