The way Aaron Sachs holds his eight-month-old daughter betrays a tentativeness that most first-time dads don't have. Roque (pronounced Ro-KAY) is perched on his knee as he sits at a picnic table in the verdant back yard of a mid-century ranch-style house in Riverside, California, that belongs to Roque's grandma. It's the week after Christmas, and the electric candles are still in the windows. Sachs has just taken the wriggling, dark-haired bundle of joy from her mom, Aimee Carrillo Rowe, an attractive 45-year-old professor. As he cradles her, Sachs, 31, also a professor, gently rubs Roque's back, then sets her down to crawl across the picnic table.

"The last time I was here, she wasn't crawling," Sachs says, gazing at her with big warm eyes. "She doesn't look that much different this time, but she seems happier." This is only Sachs' sixth visit with his daughter. He and Rowe are not a couple—in fact, both prefer women. Sachs has a new girlfriend in Oakland, where he lives. Since arriving three days ago, Sachs has been sharing babysitting duties with Roque's grandmother, Alicia ("my co-parent," Rowe, who's currently single, says), when Rowe needs a break. She's got a hair appointment right now, actually, so she takes off, and 30 minutes later Roque starts to get fussy.

"Should I put her down for a nap now?" Sachs asks.

"I didn't want to put her down until Aimee came back," Alicia says.

"Aimee said that if it seems like she's tired, to do it," he replies. As Alicia takes the baby inside, Sachs explains that he's been reluctant to make even the smallest parenting decisions. "If Aimee asks, I'll give my opinion," he says.

Sachs and Rowe first met five years ago, when he was a media-studies grad student at the University of Iowa and she was his professor. Soon after, Rowe, desperate to have a child while she still could, conceived with the sperm of a high-school friend but lost the baby. When the friend handled the miscarriage poorly, she decided to try again with a different guy and thought of Sachs. "I stuttered and stammered," she recalls. "I felt like I was asking someone on a date—but for the rest of our lives."

Sachs, himself the child of a sperm donor who was raised by two moms, had always told himself he'd be willing to donate to the right woman. "I had to ask myself, was Aimee the kind of woman I wanted to be mothering a child I helped make?" he says. After he agreed, they met three times so that Sachs could pass her his sperm in a cup. After their last meeting in July 2010, he and Rowe went surfing together in Bolinas, just north of San Francisco. That, they joke, must have been what did the trick.



Sachs represents an increasingly common and almost entirely overlooked type of dad: He's a "known donor" who chooses to be a part of his offspring's life. Such men, be they gay or straight, give their sperm to a female friend and sign away their legal rights to the child (inasmuch as their individual state's laws allow them to), yet are happy to come over on Sundays and holidays. The recipients of their donations tend to be lesbians, single or coupled, who can't afford sperm banks or want their child to grow up knowing his or her father. The donor dads often have relationships with their progeny that resemble those of divorced fathers who don't have custody—only without the responsibility of financial support or the emotional baggage of a marriage gone bust. Call it fatherhood lite.

"I get the best of both worlds," says Dean Haspiel, 44, a graphic novelist in Brooklyn who two years ago donated sperm to a lesbian friend. "I get to visit and be the kooky, fun cartoonist uncle who happens to be the biological father, but I don't have the burden of real babysitting." That's the upside. The downside is that casual fatherhood can turn out to be much more complicated than these pseudo-dads bargained for. Moms who find themselves in financial trouble or split with their partners can sometimes demand child support or more parenting time from donor dads. Or they can cut off the dad's relationship with the kid altogether. And sometimes the fathers find themselves unhappy with the limitations of the arrangement, yearning for more time with their children. "You have to talk out all your feelings before you do this," says Judith Stacey, a professor of sociology at New York University who's written extensively on nontraditional families. "You have to get out your fantasies and also be honest about what's the least you can tolerate."

No nationwide statistics exist, but experts suggest that a sizable number of the 2 million children being raised in same-sex households in the U.S. came from known donors. And that doesn't account for straight women who conceive with the help of a friend. The popularity of known-donor dads has swelled so much in recent years that the advocacy organization Single Mothers by Choice recently devoted a section of its message board to them: There, women discuss how to ask a guy to become a donor, draw up a legal statement of intention, and explain the arrangement to family, friends, and the kids themselves.

The trend appeared on the cultural radar in the late nineties when David Crosby became the donor to Melissa Etheridge's then-girlfriend, Julie Cypher, producing two kids. In recent years, variations on the idea have surfaced regularly in movies and on TV: Take the straight-guy fantasy depicted in 2004's She Hate Me, in which countless hot lesbians pay one lucky man to knock them up; or 2010's The Kids Are All Right, in which two teens raised by lesbian moms develop a relationship with their (formerly) anonymous donor dad; or The Switch, which featured an "insemination party" where Jennifer Aniston uses a friend's sample to get pregnant. This month's Friends With Kids also plays on the idea of a woman running out of time who goes to bed once with a platonic friend to conceive a child. And last October, in the HBO series Bored to Death, Zach Galifianakis spends quality time with the son he fathered for two lesbians. (Galifianakis' role was based partly on Haspiel, who drew the show's "Super Ray" comic strip.)