Tulsi, 31, was administered the oath of office by the John Boehner, Speaker of the House of Representatives.
"I chose to take the oath of office with my personal copy of the Bhagavad-Gita because its teachings have inspired me to strive to be a servant-leader, dedicating my life in the service of others and to my country," Gabbard said after the swearing in ceremony on Thursday.
"My Gita has been a tremendous source of inner peace and strength through many tough challenges in life, including being in the midst of death and turmoil while serving our country in the Middle East," she said explaining the reasons for taking the oath of office on Gita.
"I was raised in a multi-racial, multi-cultural, multi-faith family. My mother is Hindu; my father is a Catholic lector in his church who also practices mantra meditation. I began to grapple with questions of spirituality as a teenager," Gabbard said.
"Over time, I came to believe that, at its essence, religion gives us a deeper purpose in life than just living for ourselves. Since I was a teenager, I have embraced this spiritual journey through the teachings of the Bhagavad-Gita.
"... In so doing, have been blessed with the motivation and strength to dedicate my life in service others in a variety of ways," she said.
Proud of her Hindu religion, she is not Indian or of Indian heritage. Her father Mike Gabbard, is currently Hawaii State Senator and mother Carol Porter Gabbard is an educator and business owner.
At 21, she became the youngest person elected to the Hawaii Legislature. At 23, she was the state's first elected official to voluntarily resign to go to war. At 28, she was the first woman to be presented with an award by the Kuwait Army National Guard.
Early during the Democratic National Convention, Gabbard spoke from stage along with Nancy Pelosi, the Democratic Party leader in the US House of Representatives.
Currently, a Company Commander with the Hawaii Army National Guard, who has volunteered to serve on two deployments to the Middle East, Gabbard served as Hawaii's youngest state representative in 2002 and is the youngest woman in the USA to be elected into such a position.
She was endorsed by the US President Barack Obama during the election campaign.
Having never visited India so far, Tulsi says she is looking to make her first trip to India as an elected member of the House of Representatives.
"As a Vaishnava, I especially look forward to visiting the holy sites of Vrindavan," she had told PTI in an earlier interview.
Tulsi's spiritual lineage is the Brahma Madhva Gaudiya Sampradaya. She is a disciple of Jagad Guru Siddhaswarupananda Paramahamsa who is disciple of AC Bhaktivedanta Swami.
Jagad Guru Siddhaswarupananda Paramahamsa is a co-founder of the World Vaishnava Association, an umbrella organization of over 30 India-based and world-wide missions adhering to and promoting Vaishnava teachings.
Notably Hawaii is comprised of a majority of Christians with a significant number of Buddhists (10-15 per cent of the population). The number of Hindus living in Hawaii is relatively small, with only two Hindu temples in the entire state, the Iskcon Temple on Oahu and the Aadheenam Temple on Kauai.
Her religion, Tulsi said was not an issue for the election, neither it has been a negative factor in her electoral campaign, she noted. Tulsi was born in 1981 in Leloaloa, American Samoa, the fourth of five children born to a Hindu mother and a Christian (Catholic) father.
At the age of two, the family moved to Hawai'i, the 50th state of the US, also known as the "Aloha State"; which is also the birth place of the US President Barack Obama.
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