Peter Leo Byrne was the 14th child to be born to the Irish couple, James and Mary Byrne, who married in Perth on 11 September 1892 (Marriage Reg.No.273/1892). Their first, a son, died aged 5 days at Southern Cross. The second, also a son, died at 3 months. Then followed 8 girls and 3 more boys before Peter Leo was born. It is not known if there were any further children added to this family after Peter.