It's a typical night in the Brooklyn, New York, home of Stavros Tripi and his partner, Grahame Hubbard. The sound of little feet and gleeful giggles fills the air as 18-month-old Harlow, in PJs with rainbow-coloured snails, and her three-year-old sister, Tallulah, dart between the kitchen and the sitting room. Toys and teddy bears are scattered everywhere in their wake.

But this family is anything but typical. The girls' two dads watch the entire show, smiling as they patiently clean up the mess. And none of this would have been possible without the couple's close friend Jennifer Ross. Because five and a half years ago, Jennifer donated the eggs that would eventually become these two adorable little girls.

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Jennifer is a trim, blond 33-year-old with an easy smile. The event planner first met Stavros and Grahame in Toronto in 2002 when she and Stavros worked on a project together. "I instantly loved them," she says, sitting cross-legged on the couch of her Manhattan apartment, hands wrapped around a cup of tea. "They were like the older brothers I never had."

Right around the same time, Jennifer befriended - and started dating - Stavros' brother. Their relationship continued on and off for over five years. "I always had a separate relationship with the two boys - I call Grahame and Stavros 'the boys,' " she explains. "It was funny: Whenever Stav's brother and I were on the rocks, the boys would say, 'Don't worry, if you break up, we'll still be in your life.' And I honestly didn't worry because I loved them so much."

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Rocky road to fatherhood
Both men always wanted a family. "That's one of the things that drew us together early on," says Stavros. "But we waited a long time because of our careers. And eventually we realized we were also nervous because we didn't know anything about the process. It's different when a traditional couple want to have kids; it's part of the whole social fabric. We had to investigate." The couple considered adoption, but it was important to Stavros that the kids be biologically his. "I come from a big family and I really wanted to see myself in my kids' eyes."

The practice of hopeful parents using an egg donor and a surrogate is one that you hear about occasionally - Elton John and David Furnish had a son via this method in 2010; singer Ricky Martin had twin boys the same way - but the science behind it was developed relatively recently. The first baby created from an egg fertilized outside the womb was born in 1978. The first IVF (in vitro fertilization, in which fertilized eggs are implanted into a patient's uterus) clinic in Canada opened in 1983. Before that, the primary option for gay men who wanted a family was adoption.

Luckily for Grahame and Stavros, a friend had gone the surrogate route and talked them through what to expect. "We found out that it was important to do it in California because California is the only state that legally protects whoever intends to be the child's parent through the surrogate process," explains Stavros. "There's no risk of the surrogate or the egg donor fighting for custody. And you don't want to be in the middle of something like that, especially because at the time we didn't yet know who those people would be."

The couple didn't seriously consider Jennifer at first. "We joked about me donating the egg," she says. "But I wasn't sure it made sense, and I said no." They went ahead and hired a donor and a surrogate, but the transfer was unsuccessful.

"A few months later, I met the boys for dinner and they explained how the egg hadn't taken. I'd never seen Stavros so upset. I don't know what it was; I thought, 'Wow, this is what they have to go through to have a child.' I went home and called Stavros' brother - we were still together - and said, 'What are your thoughts if I donate?' And he, as calm as could be, said, 'I'd be okay with that.' So I wrote the boys an email saying how much it would mean to me if I could help them. Two months later I started the process."

"Jen's email was beautiful," says Stavros. "We're firm believers that everything happens for a reason, and when it didn't work out with the first donor, we took a step back. We started thinking, 'Our child could take 50 per cent of their traits from the donor and we don't really know that person. You have their medical history, you see photos. But are they a good person?' Maybe it should be someone we know."

They didn't start out thinking this way. In the beginning, the couple didn't want the donor to be a friend or family member. "We wanted it to be a business transaction and to keep emotion out of it. And we wanted to be 100 per cent parents to our children," says Stavros.

"We have a lot of girlfriends who would have been happy to help," adds Grahame. "But they were starting to want children of their own or to feel like they'd missed out by not having kids. We felt the same way ourselves, so we understood that. But we worried that their donating eggs would complicate our friendships."

Jennifer, however, was 27 at the time and nowhere near wanting her own kids yet. The men also knew her family and felt comfortable with them. "So we thought, 'Let's do it,' " says Stavros. "Let's go with Jen."

The reality of being a donor
The egg-donation process has several stages: First, the donor takes a combination of hormones, generally via daily injections over nine to 12 days. The hormones are designed to speed up the eggs' growth and control their release. When a doctor judges the eggs to be ready, the donor is given another hormone that starts ovulation. Within 36 hours, the eggs are retrieved through a minor surgical procedure.

In order to be cleared by the San Diego agency that Stavros and Grahame were working with, Jennifer met with lawyers, gave her medical history and underwent psychological exams to verify she was mentally stable. Then the physical part began: "I remember the day the kit with all the hormones arrived," Jennifer says. "It was in a freezer box with all these needles, and I thought, 'Oh my God. What did I sign up for?' "

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