Sara Hamilton tries to describe/ solve the mystery of La Dunne, especially why Irene came across as rather reserved in public. Maybe the explanation given by Ms Hamilton is partly true but I personally think that Irene was an intelligent woman who simply knew that she had more to lose than to gain being too open-hearted in Tinseltown. And probably nobody still alive knows what kind of experiences Irene made in the theater world...
This wasn't the first time that I read that Irene had to care for her family after the death of her father - something I really wonder about, but I still have the hope that it wasn't as tough as that.
Certainly beyond the huge personal loss, Joseph Dunn's death changed the financial situation of the family. Maybe this was one reason why Adelaide - Irene's mother - moved Irene and Charles to her hometown Madison. Probably living there was cheaper than in St. Louis and Charles Henry - Adelaide's father - was a well-known builder of boilers for steamboats and could affort to sell a house to his daughter for the symbolic amount of one Dollar.
That Irene who described herself as "a serious person to start with," early developed a sense of responsibility is something I don't doubt. She described an idyllic youth in Madison which does not sound like all kind of eyes looking "to Irene for some solution to the problem." Nonetheless, Irene probably wanted to stand on her own feet/support her family financially early in life.