[1] Marion O'Shea Roosevelt was born in 1850 in Nenagh, County Tipperary.
Her parents were John and Mary Anne O'Shea (née Gill) of Summerhill, Nenagh.
Her older brother John Augustus was a soldier, journalist and novelist, and her sister Elizabeth was a writer who emigrated to India.
Another sister, Margaret (Mrs Kelly) (1854–1927) was noted as being fluent in a number of languages, and translated French works, and her brother Robert Gabriel (1854?–1882) was the London political correspondent for the Freeman's Journal.
[3][4] They had three children who were referred to as Robert's stepchildren:[5] Roosevelt published articles and poems in American journals.