All it says in Wikia is- After hitting rock
bottom in an unhappy marriage- Irene
starts drinking heavily as a coping mechanism.
She was played by a different actress for first
couple of years. Pippa & Michael were fostering
her children.
I remember being shocked at the time by
how "loud etc" she was. Didnt seem to
fit into.Summer Bay.Now shes one of the
stalwarts!!