This is of interest to me. My family are from Ballyshannon, Co Donegal. Terence O'Brien and his wife Maggie (nee McDermott) had four daughters, the eldest twins give, on the1901 census their age as 20 yrs (Born 1880) and place of birth as "America" the other daughters where born in Ballyshannon. The father, Terence, died in Ballyshannon in 1887. His occupation is given as "Labourer". It seems unlikely that a "labourer" would have been able to afford to return to Ireland with a wife and two infants. I knew my twin great aunts, and was aware that they were American citizens. Patrick Haynes in Sunny Sydney