Twins Brian and Daniel Winterfeldt look so much alike their own mother can't tell them apart at times. In fact, they can't even tell themselves apart in childhood photos.

Each has gone through his entire life seeing himself in the face of his brother, so it's fitting they've taken parallel careers paths.

As Big Law partners, Brian practices in Mayer Brown's Washington DC office, which he joined two years ago to handle intellectual property matters, and Daniel works in Reed Smith's London office, where he focuses on securities issues.

But Big Law is not all they have in common. The 44-year-old lawyers are both openly gay, and they are adamant about improving the lives of lesbian, gay, bisexual and transgender (LGBT) people. Both have worked for LGBT rights in the legal profession and in their communities, and the challenges they've encountered in a field dominated by straight white men have spurred them to advocate for those rights, they say.

"I feel like I'm held to a different standard," says Brian, who counts Google, Facebook, Apple and Calvin Klein as some of his clients. "We're in a similar boat as women. We have to work twice as hard to get half as much. I feel like I have no choice to be a superstar."

Daniel, a 1999 graduate of Fordham University School of Law, serves on the executive committee of The Trevor Project, a provider of suicide prevention and crisis management services for lesbian, gay, bisexual, transgender and questioning youth. He also handles pro bono matters for diversity-related organisations and is a member of the National LGBT Bar Association.

Brian, a 1998 graduate of the Georgetown University Law Center, says he's had experiences in London similar to his brother's as a gay Big Law partner.

"You have to do a lot more to sit at the table," he says. "It is a challenge getting recognised."

In 2008, Daniel founded the InterLaw Diversity Forum in London. The network has about 3,000 members and supporters from more than 70 law firms and 40 corporations and financial institutions. The InterLaw Diversity Forum has since launched the Apollo Project, a resource for organisations to learn best practices to increase diversity.

Daniel was motivated to establish the InterLaw Diversity Forum, in part, because at the time no London law firms were included in the Stonewall Workplace Equality Index, which identifies top employers for LGBT individuals.

The percentage of openly LGBT lawyers generally has trended upward since 2002, according to the National Association for Law Placement (NALP), which tracks the numbers in major US law firms. In 2002, the number of openly LGBT lawyers reported was less than 1% of the total lawyers represented. NALP says It took until 2012 for the overall percentage to exceed 2%.

The overall percentage of lawyers reported in 2016 increased to 2.48%, a small amount compared with the 2.34% of 2015. The presence of LGBT lawyers continues to be highest among associates, at 3.24%, and was up from the 3.08% reported in 2015.

It isn't surprising that the Winterfeldts' professional and philanthropic lives have run parallel, given the twins' history. In school, teachers were "incessantly concerned" that they would play a trick by switching places, Brian says. (The boys, who grew up in Cincinnati, were enrolled in separate classes.) In second grade, they were hauled to the principal's office for trying to pull a fast one.

"We had not switched," Brian says.

A penchant for reading and writing and a desire to help other people made law school a logical choice for the Winterfeldts. They made the decision to join Big Law because it was a challenge, especially as gay men, they say.

"I have a stubborn streak," Brian says.

The brothers are not bitter about their experiences in Big Law. They say most of the bias is unconscious and that law firms have done much in recent years to help address shortfalls in diversity overall. They remain committed to working at large firms, partly to smooth a path for LGBT lawyers who follow them.

"There is a real effort within Big Law to change," says Daniel, who joined Reed Smith last year from CMS Cameron McKenna.

Keith Wetmore (pictured), the first openly gay Am Law 100 chairman, who came out to his firm, Morrison & Foerster, in 1982, says that the "opportunities are very strong", today for gay lawyers in large law firms across the country.

These days, most major law firms have LGBT affinity groups, organisations created by many of them more than a decade ago, amid a strong associate hiring market and calls from clients to improve diversity. In addition, openly LGBT associates are better represented at large law firms: those with 700 lawyers reported that 3.81% of their associates were openly LGBT, according to the the NALP.

But difficulties remain for LGBT lawyers in developing business with some clients, Wetmore says. He also notes that strong biases exist against transgender lawyers.

"Transgender issues can be as foreign to a gay man or a lesbian as [to] our heterosexual friends." But, he says, gay lawyers possess "special insight as a sexual minority" and that they have "a special reason to be on the side of transgender rights".

For Brian and Daniel, a career in the law melds well with their commitment to LGBT individuals.

"We have a sense of justice and fairness," Daniel says. "We want to help people."