WASHINGTON/NEW YORK (Reuters) - Gay and lesbian couples should be able to get married for the health and well-being of their children and families, the nation’s leading group for pediatricians said on Thursday in a policy statement that also backs adoption rights.

Bernie Liang and Ryan Hamachek show their rings after getting married outside Seattle City Hall in Seattle, Washington December 9, 2012. REUTERS/Cliff Despeaux

The American Academy of Pediatrics, in calling on the legal right for same-sex couples to marry, said children’s well-being is affected far more by other factors such as their parents’ health and economic security than their sexual orientation.

“It is better that children have two parents than one parent, and assuming that these parents love each other and love the child and have economic and social security and stability, then that’s the critical ingredient for the optimal growth and development of the child,” said Dr. Benjamin Siegel, head of an AAP committee that studied the issue.

Siegel said the academy’s board of directors voted unanimously for the organization, which represents 60,000 pediatricians, to support same-sex marriage as well as the right for gay parents to adopt or foster children.

“We need to have laws and regulations that support families to nurture children,” said Siegel, a pediatrician at Boston Medical Center and the Boston University School of Medicine.

The U.S. Supreme Court is preparing to take up two major gay rights cases next week, one on federal benefits for same-sex married couples and another on California’s law defining marriage as between a man and a woman.

Recent Reuters/Ipsos polls have found a majority of Americans support same-sex marriage and access to federal benefits such as such as tax exemptions for a surviving spouse’s inheritance.

Close to 2 million American children already are being raised by gay and lesbian parents, according to the pediatric group.

THE KIDS ARE ALL RIGHT

The group previously backed allowing a biological parent’s partner to adopt a child and allowing same-sex spouses to receive federal benefits.

But its new statement, published in the journal Pediatrics, is based on more recent data showings kids do just as well when they are raised by parents of the same or different genders.

“Scientific evidence affirms that children have similar developmental and emotional needs and receive similar parenting whether they are raised by parents of the same or different genders,” AAP said, citing research over the last 30 years.

One 2010 study in the journal Pediatrics found teenagers with lesbian moms performed better in school and had fewer social problems, for example, when compared to teens with a mother and father (reut.rs/i7bS6w).

Some gay rights opponents have questioned the long-term effects of gay marriage on children.

“There cannot yet be decisive evidence,” George Will, a conservative columnist, wrote in The Washington Post last week about whether same-sex marriage was harmful.

Nine states and Washington, D.C., have legalized same-sex marriage. Public and political support for marriage equality has grown in recent years and on Monday, former Secretary of State Hillary Clinton became the latest politician to come out in favor of same-sex marriage.

The pediatrician’s group said marriage, not civil unions, is key because it offers families stronger economic security and helps avoid issues of discrimination, intolerance and inequality that can affect parents’ self-esteem. Various state laws on adoption by gay and lesbian parents are also “an inconsistent patchwork,” it added.

In Massachusetts, where same-sex marriage has been legal since 2004, Siegel sees broad acceptance of kids with gay or lesbian parents.

“My experience is that parents are happier (and) the kids are fine,” he said.