Your personal life isn’t supposed to matter when you apply for a mortgage. For most borrowers, the important questions are just math: Are you buying the home at a fair price, and do you earn enough to afford the monthly payments?
But for same-sex couples, the calculus may be more complicated. A recent study of lending patterns nationwide suggested that same-sex couples are being approved for mortgages less often than other similarly qualified borrowers and that they’re paying more for the loans they get.
The research, conducted at Iowa State University and published this spring in the Proceedings of the National Academy of Sciences, found that same-sex couples were up to 73 percent more likely to be denied mortgages and that they paid interest rates as much as 0.2 percent higher.
The finding, which looks at transactions dating as far back as 1990, has raised concerns among civil rights activists, who say it highlights a problem that is difficult to spot. Discrimination in mortgage lending can be impossible for even its victims to detect reliably.
“You get turned down, and it’s not like they tell you, ‘We’re turning you down because you’re a same-sex couple,’ ’’ said Karen L. Loewy, senior counsel at Lambda Legal, which advocates for the LGBT community and people with HIV. “The reasons that folks are given are usually more innocuous, and I think folks don’t generally suspect that discrimination is playing a role.’’
Some in the mortgage industry, however, say they are skeptical that the effect of discrimination is as pronounced as the study suggests — especially in Massachusetts, a national leader in LGBTQ protections and the first state to grant marriage rights to same-sex couples.
“Lenders make money when loans close, so there is zero economic incentive to deny loans more than the risk profile represents,’’ said Mike Kemple, senior vice president at Bridgewater Savings and a board member of the Massachusetts Mortgage Bankers Association. “I don’t know how that can be true here locally.’’
He said that underwriting decisions are generally made based on the requirements of third parties — other banks that will ultimately hold the mortgages as financial investments — and that bankers often rely on algorithms to help them decide clear-cut cases. There are also many laws in place — a prohibition on discouraging someone from filing a loan application, for instance — that would make widespread discrimination unlikely.
But though Massachusetts laws prohibit discrimination in lending based on sexual orientation or gender identity, federal housing discrimination law offers no similar protection for LGBTQ people.
Because the US Fair Housing Act is so influential over housing policy nationwide, the absence of protections for same-sex couples makes the prevalence of the practice difficult for either regulators or consumers to spot.
Hua Sun and Lei Gao, the Iowa State finance professors who carried out the study, said they got into the issue mostly as a way to see whether the practice could be studied at all. The federal government doesn’t keep any data on loans to same-sex couples, and there is no way for them to self-identify on application forms.
But prospective borrowers do have to disclose their genders, and Sun and Gao found that by looking at loans where both the applicant and co-applicant are either men or women, they could get a general sense for the population of same-sex couples.
They said the number of same-sex couples they found using this method corresponds to other data showing gay, lesbian, and bisexual people as a portion of the general population.
In an interview, Gao acknowledged that there is much more work to be done to understand the issue fully; the study would have no way of spotting denials for single borrowers who are facing discrimination, for instance. But he believes his study has amplified the conversation around a topic that has been poorly understood.
“I think this paper is making some positive impact on this issue, and hopefully there will be more follow-up research and follow-up regulations,’’ he said. “I was not that surprised actually, because I feel, when I read the news, that there are some people who don’t like this group, and they don’t hide their feelings.’’
Whatever discrimination is happening in mortgage lending appears to be subtle enough that the borrowers do not recognize it or do not think they can prove it.
The Massachusetts Commission Against Discrimination, the state Mortgage Review Board, and the office of state Attorney General Maura Healey all said they have received no complaints about discrimination against same-sex couples seeking mortgages.
Lambda Legal and GLBTQ Legal Advocates & Defenders — the Boston-based civil rights organization known as GLAD — also said they haven’t gotten any complaints. But they urged people to come forward if they suspect they have been mistreated.
“We do know that discrimination in housing is prevalent despite protective fair housing laws, and it tends to impact the most marginalized people within our community, including LGBT elders and people of color,’’ GLAD staff attorney Chris Erchull said in an e-mail. “It is important to familiarize yourself with the loan approval process and ask questions, especially if your application is unexpectedly denied.’’
Kathleen C. Engel, a professor at Suffolk University Law School, said the paucity of federal data makes it difficult for any researcher to draw concrete conclusions about discrimination against same-sex couples.
And that gives cover to those who would discriminate, Engel said.
“The failure to collect data impairs the enforcement of antidiscrimination laws,’’ she said. “The federal government in particular has entered a kind of data-free zone since the 2016 election, so we just don’t have the information we need as researchers to find out whether discrimination is taking place.’’
But there is evidence that LGBTQ people face housing discrimination, particularly in renting, where the relationship between tenant and landlord is more direct than that between borrower and banker.
A 2013 study by the US Department of Housing and Urban Development found that same-sex couples got significantly fewer responses to e-mail inquiries than their heterosexual counterparts, for example, and that state-level antidiscrimination laws didn’t help.
And a 2017 study by Suffolk’s Housing Discrimination Testing Program found that transgender applicants were treated worse than other people seeking rentals.
Loewy, of Lambda Legal, said she hopes the research into mortgage lending helps more people understand their rights.
“I don’t think people get that it is a trend,’’ she said. “It’s not until you see studies like [this one] that people have a sense that they’re being turned away for discriminatory reasons.’’
Andy Rosen can be reached at firstname.lastname@example.org. Follow him on Twitter @andyrosen. Subscribe to the Globe’s free real estate newsletter — our weekly digest on buying, selling, and design — at pages.email.bostonglobe.com/AddressSignUp. Follow us on Facebook, Instagram, and Twitter @globehomes.