When U.S. Secretary of Defense Ash Carter announced on Thursday that transgender men and women could serve openly in the military, Captain Jennifer Peace was overjoyed.

“I’ve been fighting for this and waiting for this for so long that it was much more emotional than I anticipated. I had to take a moment to let those feelings sink in,” Peace, a 30-year-old military intelligence officer, told NBC OUT.

“Everything we’d been saying - that transgender people are fully capable of doing this job and that our service matters and is valued just like every other service member - it’s just amazing to hear those kinds of things from senior leadership,” she added.

U.S. Army Captain Jennifer Peace Jennifer Peace

Peace is not alone in her joy. The decision to lift the ban on transgender people serving openly could affect thousands of active service members. The exact number, however, is unknown.

According to the RAND Corporation, a private research group contracted by the Defense Department to explore the impact of trans personnel on the military, the number of transgender individuals currently serving in the active component of the U.S. military is somewhere between 1,320 to 6,630 (out of a total of about 1.3 million service members).

A separate report from the Williams Institute at UCLA, however, estimates the number to be significantly higher - about 8,800. This has led some researchers to speculate that transgender people join the armed services at a greater rate than people in the general population - and gender identity may be part of the reason.

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“What some people have suggested is the higher prevalence of transgender people in the military is [due to the perception that it] is a very gendered institution. So if gender is something a person is struggling with, they may see the military as a place where they would be forced to maintain a particular gender norm,” said Gary Gates, a researcher who helped author the Williams Institute study.

“The military would be a place that would force [you] to maintain [your] gender as it is and keep those kinds of gender norms in place, if you’re struggling to potentially transition,” Gates added.

But some take issue with this speculation, arguing transgender service members join the military for the same reasons as everyone else.

“When you ask transgender service members why they joined the military, the first reasons they say is the same [as everyone else]. It’s ‘to serve my country,’ or ‘it was a way to get an education,’” said Sue Fulton, President of SPART*A, an LGBT military group.

Peace said the idea that transgender people join the service as a way to deal with gender dysphoria is a “a gross misunderstanding of trans people.”

“That’s a caricature those not involved in the community would think of us. I didn’t join the military out of any sense of masculinity. People join the military for a lot of different reasons. They’re all very personal,” she said.

U.S. Army Infantry Soldier Patricia King Patricia King

Patricia King, a 35-year-old infantry soldier, admits issues surrounding her gender identity did play a role in her decision to enlist.

“I was aware at the time that I was transgender, or at least understood the feelings I was having, but I didn’t know what I wanted to do with my life. I didn’t know who I was, and I didn’t understand my feelings,” she said.

King, who enlisted shortly after high school, said she hoped the military would help her “answer some of those questions.”

“I decided I would go into the infantry. I thought it was a contrast to the feelings I was having, and it would help me to either understand or get rid of those feelings,” she added.

Joining the military, however, did not help with "those feelings."

“I still felt out of sorts with my body and as though something wasn’t right, and ultimately that led me to a decision that I wanted to transition and live an authentic life,” King said.

While gender identity may have been a factor in King's decision to enlist, she was quick to point out that everyone’s reasons are personal.

“I think people’s decisions for enlisting are as varied as we are, but what’s important is when you put on that uniform you are prepared to serve and do your job."

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