Melissa Singer always knew she didn't want to get married. It wasn't that she didn't like men, or relationships; she just never felt the desire for constant partnership. What she did want, however, was a child.

"Motherhood was the thing I wanted to do most in the world," said Singer, who lives in New York City. "I wanted to have a child. I wanted to be able to pass along the traditions that my family had. I wanted to be able to give my parents a grandchild."

So, in her mid-30s, Singer went to her doctor and said she wanted to start a family. The doctor gave her the phone number of a local sperm bank. After nine months of trying to conceive, Singer became pregnant with her daughter, Jacqueline, now 14.

Stories like Singer's have gotten a popularity boost in pop culture this summer with movies like "The Back-Up Plan" and "The Switch" focusing on parenthood via donor insemination. The latter movie sparked a minor feud between lead actress Jennifer Aniston and conservative pundit Bill O'Reilly, who said in August that Aniston's comments on women's ability to become mothers without men were "destructive to our society," and diminished the role of the dad.

Singer mostly rolls her eyes at what she calls "the same blather we've been hearing for decades." And most scientists who've researched "choice moms" who deliberately decide to raise children alone say that the kids do well. There are some reasons why: Most choice moms are highly educated, well-off financially, and, by definition, very deliberate in their decision to have a child — all generally good things for children.

The question now, many parents and researchers say, is not whether sperm donation is a valid way to have a child. It's whether the anonymity of sperm donation ultimately hurts the donor's offspring.

The truth about where (donor) babies come from

Decades ago, sperm donation was kept under a veil of secrecy. Couples with fertility problems who came to doctors were often given the sperm of medical students. Few records were kept, and many children weren't told that the man they knew as their father wasn't biologically related to them.

That's still the case for many children raised by heterosexual parents. A 1996 study published in the journal Human Reproduction found that of 111 European couples who had conceived a child by donor insemination, none had told the child. A study presented at a 2008 meeting of the European Society of Human Reproduction and Embryology found that although 46 percent of parents of donor-conceived children in the United Kingdom intended to tell their child about their conception, only 29 percent actually had by the time the child reached age 7.

Single moms, on the other hand, are much more likely to tell their child the truth.

Research on a sample of mostly American donor-conceived kids published in 2009 in Human Reproduction found that 9 percent of heterosexual couples told their kids about their conception before age 3, compared with 63 percent of single moms. Early disclosure could put single moms' kids at a psychological advantage over the two-parent children. The study found that children told after age 18, for example, were more likely than children told at earlier ages to feel "angry" or "shocked" at the news.

"The sooner they're told, in a fairly matter-of-fact way, the better," Eric Blyth, a professor of social work at the University of Huddersfield in the United Kingdom and a visiting professor at Hong Kong Polytechnic University, told LiveScience. Blyth compares the persistent secrecy over donor insemination to the way adoptions were run decades ago.

"I could never really see that there was such a big difference certainly from the child's point of view between adoption and donor conception, in terms of children knowing where they come from," Blyth said.

For Singer, the decision to tell her daughter the truth was simple. She introduced the idea in bedtime stories about a happy family that wanted to be bigger, so one of the women in the family had a baby. As her daughter got older, Singer added more details about doctors' visits and the differences between the way Jacqueline was conceived compared with other children. The disclosure is, in the words of another donor-insemination mother interviewed by LiveScience, "a nonevent."

Anonymity, pro and con

Even when children know how they were conceived, few know who their donor was. The U.K. passed legislation removing the promise of anonymity for donors registering after April 1, 2005. After age 18, children of those donors are now allowed to learn the identity of their donor. In the United States, sperm banks have begun releasing more information on donors, including detailed medical and family histories, but anonymity is still standard. Sperm banks are not required to track the number of births from donations, so children may also have multiple half-siblings they don't know about.

Not all donor-conceived children (or their parents) are satisfied with that anonymity. In 2000, Colorado mother Wendy Kramer and her donor-conceived son Ryan launched the Donor Sibling Registry, a website that helps donor half-siblings connect with one another. Ryan Kramer eventually uncovered six half-siblings, as well as his donor.

Kramer argues that donor anonymity benefits sperm banks instead of families, allowing the banks to sell sperm without tracking how many children are born as a result. About 1,200 donors are registered at her site, she said. One found out he'd fathered 125 children.

Anonymity, she contends, prevents donors from sharing updated medical information with their biological children. But seeking out a donor is about more than health history, she said.

"For a woman, the man is her sperm donor," Kramer said. "For a child, it's that child's biological father."

In May, the Commission on Parenthood's Future released a report on an Internet-based sample of people who were donor-conceived, arguing that donor conception was bad for children. The report's text was criticized by Blyth and others who argued that it overstated what the data actually indicated. The research was funded by the Institute for American Values, an organization that promotes traditional definitions of marriage and family.

For example, a finding that 19 percent of donor children "strongly agreed" and 26 percent "somewhat agreed" with the statement "The circumstances of my conception bother me," combined with the finding that 65 percent of donor children agreed or strongly agreed with the statement "My donor is half of who I am," was interpreted by study co-author Elizabeth Marquardt, director of the IAV's Center for Marriage and Families, as revealing "profound" struggles with "origins and identities."

"When I read the published report, I could see some things that I would have disapproved of," said Glenn Noval, a sociologist at the University of Texas, Austin, who co-authored the study but did not participate in the writing of the final report. However, Noval told LiveScience, Marquardt's focus on the negative aspect of some of the answers was "understandable."

"Elizabeth may overestimate the negative attitudes, but they seem to be there," he said.

Mixed opinions

Opinions on anonymity in the donor community are mixed, even among children. For every child with a burning curiosity about his or her donor, there's another with only mild interest, or none at all.

Hanne Anderson, 21, was raised by her mom in Mobile, Ala., who used donor sperm to conceive her. While she might consider a search for half-siblings or her donor one day, Anderson said, she hadn't given much thought to the legality of anonymity.

"I think as far as details regarding a person's name or any way to contact them, I don't see anything wrong with that being anonymous," Anderson told LiveScience. "Of course, when you get into ethnicity and the more scientific aspects, I think that should always be made available."

Singer thinks that the practice of anonymous sperm donation will eventually come to an end. However, she said, "I'm not sure that I feel that it's fair to the guys who agree to donate under conditions of anonymity to break that open without their permission."

Singer's daughter, Jacqueline, has met one half-sibling through the Donor Sibling Registry. The two had little in common except for their donor's nose, Singer said. As for meeting her donor, Jacqueline has so far been satisfied with the biographical sketch provided by the sperm bank.

"My daughter has curiosity about who he is," Singer said. "But it's not a tremendous curiosity."