Secrets

Recently, my dad mentioned that my mom jad a savings account with over $40,000 in it. She had never told my dad about it and he didn't know the purpose. Dad split it up and gave it to the grandkids. (Later I remembered that mom had Nancy & me sign cards and said the account was in trust for us.)
This got me thinking about other things she kept from him. It taught me that it was OK to keepthings from your spouse. I wonder if dad kept secrets from mom. (I asked and the answer was no.) Did mom's parents keep secrets from each other?
Secrets are big. Post Secret shares anonymous secrets each Sunday with millions of people. Some of these secrets shock me, some make me laugh, some make me sad. Most the secrets make me think of my own secrets. Some of innocent and harmless. Some are self-denial. Some I wish I could take back.
What makes us keep secrets? Some secrets are for fun. We don't tell our family what we bought them for Christmas so they can be surprised when they open the gift. We don't tell people that we pick our noses because it's gross. We keep our PIN numbers secret to protect our personal records secure.
But should we keep secrets from our spouses/partners? Is it OK to keep a secret savings account just in case?