Danny Boy" is a song whose lyrics are set to the Irish tune "Londonderry Air". The lyrics were originally written for a different tune in 1910 by Frederick Weatherly, an English lawyer who never actually visited Ireland, and modified to fit Londonderry Air in 1913. The first recording was made by Ernestine Schumann-Heink in 1915. It has been recorded many times since then by both male and female vocalists. In the original version the name Danny could be replaced by Eily if the singer was male.
If the song is interpreted as a message from a parent to a son who is leaving home, the lyrics make sense whatever the gender of the singer.