My trigger to stop being so secretive about money occurred in a Palm Springs hot tub, while my sister and I were parboiling ourselves under a clump of shaggily glamorous palm trees. She is 61, I’m 59 and we were talking about money for the first time since the days when our “salaries” came in the form of weekly allowance from someone we called Mommy. Which is to say, we were having a meaningful money discussion for the first time in a half century.  “How much do you make?” she asked. I told her. I asked her the same question.   She answered it.  “Oh, O.K.,” we said simultaneously.  And then, as if we had walked through a heretofore unseen wall, we started talk openly about all sorts of money matters: how much money the family lost after the IRS caught up with some early-80s tax-filing shenanigans; “Mommy’s” financial situation; how much we had saved for retirement.  It was an inexpressible relief to discuss our family’s complicated relationship with money. The short story: my mother’s father made …