My dad, yes. He's always been the one good with money, and he's retiring soon (not MMM-early, but still earlier than social security kicks in). My mom...she's a spendypants and very into keeping up with the Joneses, in her country club neighborhood.
So when I tell dad I'm going to get rid of my brand new car and go to a beater or a bike, he says "great plan!" When I tell mom, she first worries I'm having money problems, then says how I earned that car, and I make good money, so I can't get rid of it. Mom's not going to hear things like that anymore.
Dad knows how much we're putting away for retirement (this year we'll max one of the 401ks, and we're paying tuition out of pocket while overpaying the mortgage to ditch PMI), and quickly went "hang on, you're setting yourself up to retire early!" Told him "yep, around age 40." Mom has only heard that stuff because I needed to reassure her after she thought I ran out of money because the joint account she and I had from when I was in college was empty. "No, mom, it's just that I'm married now, and so my husband and I are sharing a bank account at a different bank."
We both try to hint to our younger siblings about the importance of saving for retirement. My husband's parents know the early retirement goal, but none of our siblings do, though I've mentioned MMM on Facebook before. Mom knows my salary, because she's a worry-wart and this is a way to keep her calm. Dad doesn't, just trusts that he taught me well enough when I was helping him keep the books for one of his businesses.