On Monday, Blixt and a California man who has twin boys with his Israeli husband, filed a pair of federal lawsuits alleging that the U.S. government is discriminating against them and illegally denying birthright citizenship to some of their children born abroad.
In the California case, Andrew Dvash-Banks sought to transfer his citizenship to his twin boys, who were carried by the same surrogate and born minutes apart. Now one twin, who was conceived using Andrew's genetic material, has U.S. citizenship. But the other, conceived with his husband's genetic material, does not.
"The harm done to families is extreme," said Aaron C. Morris, executive director of Immigration Equality, a New York-based organization that is representing the plaintiffs. "It is discrimination, pure and simple."
The State Department had no comment on the allegations Friday, but an official pointed to a list of regulations and the agency's Foreign Affairs Manual.
On its website, the department says that to transfer a parent's U.S. citizenship to a child born abroad, "a biological relationship, or blood relationship, is required."
"The laws on acquisition of U.S. citizenship through a parent have always contemplated the existence of a blood relationship between the child and the parent(s) through whom citizenship is claimed," the website says.
The lawsuits say that rule flies in the face of the Immigration and Nationality Act, which allows children to inherit their married parents' U.S. citizenship as long as the adult has lived in the United States for five years and meets other requirements. They claim that the State Department considers Blixt's and Dvash-Banks's children born "out of wedlock," even though both couples are legally married.
If an American adopts a child from abroad, that child can become a naturalized U.S. citizen.
Birthright citizenship has flared up as a contentious political issue — including with Sen. Ted Cruz (R-Tex.) and John McCain (R-Ariz.), who were born abroad — and it has affected heterosexual married couples as well, said Ira Kurzban, a longtime immigration lawyer and author based in Miami.
He said the State Department has demanded a genetic or biological link between parent and child to deter immigration fraud or crimes such as trafficking. But the broader use of assisted reproductive technology increasingly is raising questions about whether the government's requirements are fair.
"I don't think it's a generous interpretation of the statute," Kurzban said. "It does raise serious issues of equal protection."
After the Supreme Court struck down a law barring the federal recognition of same-sex marriage in 2013, Americans in such unions could legally bring their foreign spouses to the United States for the first time.
Many had previously moved to other countries and started families, in part because they were not considered legally married in some U.S. states and under federal law. They soon discovered that the new marriage rules did not ensure U.S. citizenship for their children.
Immigration Equality, which focuses on issues pertaining to gay men and lesbians, says same-sex couples are easy targets for discrimination under the policy, because they often rely on assisted reproductive technology to have children.
Morris said his organization approached the Obama administration around 2015, when the issue surfaced, and had hoped officials would solve the problem. Instead, it has spilled over into the administration of President Trump.
In interviews, the parents say they felt singled out for invasive questioning at U.S. consulates about how their children were conceived because they are in same-sex marriages. They say they are the only parents named on the children's birth certificates, and want their children to be treated the same as the offspring of heterosexual married couples.
The lawsuits say the effects of the policy are far-reaching. Noncitizen children cannot easily travel to the United States or reside in this country permanently and are ineligible to run for public office. Only people who have been U.S. citizens since birth can run for president.
The federal government denied citizenship to Blixt's son Lucas, who was born in London to her wife, Stefania Zaccari, in 2015. Zaccari is a citizen of Italy. When Blixt gave birth to the couple's second son, Massi, last year, her citizenship transferred to him. Both women were allowed to be listed on the boys' birth certificates in England because they were married at the time of the pregnancy, according to Immigration Equality.
But that did not mean Blixt's citizenship would transfer.
Blitz said she later learned that she could sponsor Lucas as his stepmother to bring him legally to the United States as an immigrant. She declined.
"The principle of that is just a bit too hard to swallow," she said. "I'm not his stepmother. I'm his mother."
In California, Dvash-Banks said the government granted citizenship to his biological son Aiden, but denied it to his twin, Ethan.
Dvash-Banks, a travel agent in Los Angeles, is married to Elad Dvash-Banks, an Israeli citizen he met while studying abroad. Both men donated genetic material to create embryos that were brought to term using a surrogate.
The couple never intended to divulge which spouse fathered the boys after the surrogate gave birth to them in Canada in 2016. To them, it was irrelevant.
In Canada, they proved their relationship to the twins through DNA testing, and a court declared them the twins' parents on their birth certificates.
"No one, not even our parents, knew," Andrew Dvash-Banks said. "We just wanted to stress that we are a family. The four of us are unbreakable."
The U.S. consulate later required them to undergo additional DNA testing. When they went to the consulate in Toronto to register the twins and seek U.S. passports, they were stunned to learn that only Aiden is considered a U.S. citizen.
The couple has since moved to California, where Andrew Dvash-Banks's extended family lives. Ethan's tourist visa expired in December.
Andrew Dvash-Banks has applied for a green card for his son, a status that falls short of birthright citizenship and typically would be sought only if his father was an immigrant who had become a U.S. citizen, rather than an American citizen from birth.
"It's awful," Dvash-Banks said. "We love our children so much. I can't let my child be treated differently from his twin brother because of this. It's not right."