Although O'Toole has previously given his birthplace as Connemara, County Galway, he has himself suggested that this may not be accurate in the first volume of his memoirs, Loitering with Intent, saying that this was the "family version", and that he may have been born in either Kerry, Dublin, or, perhaps, Leeds, England. To avoid such complications for his children, he has ensured that both his daughter Kate and son Lorcan were born in Dublin. Elder daughter Patricia was born in England, a mistake which O'Toole regretted, famously saying: "Pat was born in Britain, the poor thing."
In her own memoir, Public Places, his former wife Siân Phillips says, "...he may or may not have been born there, but he is a true son of Connemara." His father, Patrick Joseph O'Toole was an Irish bookmaker and his mother, Constance Jane Eliot (née Ferguson), was a Scottish born nurse.