Catherine was the daughter of Patrick McGillain (McGillen) of Bellinasulis, County Tyrone, Ireland and Mary Conway McGillain (McGillen) of Letterkenny, County Donagal, Ireland. Mary and Patrick were married in Letterkenny, County Donagal, Ireland. (Date is unknown). Mary and Patrick had twelve children. They were: Michael McGillain (McGillen) was born on 17 January 1850 in Ireland; Henry McGillain (McGillen) was born on 06 January 1851 in Ireland; Mary Jane McGillain (McGillen) was born on 01 May 1853 in Ireland; Patrick McGillain (McGillen) was born on 26 May 1855 in Petersville, Queens County, New Brunswick, Canada; Frank McGillain (McGillen) was born on 05 February 1857 in Petersville Parish, Queens County, New Brunswick, Canada; Thomas McGillain (McGillen) was born on 28 February 1859 in Petersville Parish, Queens County, New Brunswick, Canada; Catherine McGillain (McGillen) was born on 28 May 1861 in Petersville Parish, Queens County, New Brunswick, Canada; William McGillain (McGillen) was born on 04 April 1863 in Petersville Parish, Queens County, New Brunswick, Canada; John McGillain (McGillen) was born on 03 January 1865 in Petersville Parish, Queens County, New Brunswick, Canada; Peter McGillain (McGillen) was born on 11 January 1867 in Petersville Parish, Queens County, New Brunswick, Canada; Joseph McGillain (McGillen) was born on 17 February 1869 in Petersville Parish, Queens County, New Brunswick, Canada; and Thomas Stephen McGillain (McGillen) was born on 06 July 1874 in Petersville Parish, Queens County, New Brunswick, Canada.

Catherine married Joseph S. Adams on Prince Edward Island, Canada. (Date is unknown). Catherine and Joseph Adams were the parents of 9 documented living children, William J., Mary Florence, Joseph D., John Byron., George Clarence, Francis H., Margaret Leona, Alice C., Isabelle Theresa. They were also the parents of an infant Adams was born and died in 1902 in Brewer, Penobscot County, Maine.

Note: "Mary (Conway) McGillen, her mother, lived with Catherine until her death on 21 September 1905, and she (Mary) was then buried in Petersville (Enniskillen) New Brunswick. Per Gramma Mary F. Adams' Birth Certificate, her mother's name was Catherine McGillain (not McGillen as on Gramma's family history) this birth certifcate confirms her birth in New Brunswick, Canada." Source: Rootsweb.

Catherine was eighty-five years old when she died.