Jennifer Natalya Pritzker is a member of one of the wealthiest families in America, so it’s no surprise that she is included on the Forbes 400 list. What has surprised many, though, is that the highly decorated former Army lieutenant who was born James Pritzker is now identifying as a female — making her the first transgender billionaire in history.

In a statement issued last month, Pritzker, 63, wrote: "As of Aug. 16, 2013, J.N. Pritzker will undergo an official legal name change, will now be known as Jennifer Natalya Pritzker. This change will reflect the beliefs of her true identity that she has held privately and will now share publicly. Pritzker now identifies herself as a woman for all business and personal undertakings."

Transgender is a term assigned to people who identify with or express a gender identity that is different from their biological sex at birth. Experts believe that any number of factors can contribute to why people are transgender. Biological theories say that genetic influences and prenatal hormone levels could contribute to transgender identification. Early-life experiences as well as events later in adulthood are also believed to contribute to the development of transgender identities.

Gender identity refers to an individual’s “internal sense of being either a male or female or, perhaps, neither.” We’re assigned a biological sex at birth. But, the thinking goes, our gender identity is formed more in the social context. Things like behavior, clothing, and voice are all forms of gender expression.

Pritzker is divorced and has three children. She is one of 48 women on the Forbes list, and is ranked at number 327. Pritzker is part of a group of 11 relatives and extended family that make the list each year. The family is among Chicago’s elite, full of well-known philanthropists. She, individually, has an estimated net worth of $1.7 billion.

Earlier this year, Pritzker donated $1.35 million towards the creation of the Transgender Military Service Initiative, which will “sponsor state-of-the-art scholarship on transgender military service, and to enhance the quality of public dialogue.”