I bet someone makes a product with this someday https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing.

You could in theory have a digital safe that you yourself can open with one key, and a quorum set of 2 keys that require both. You distribute 1/2 combination keys to your kids and keep one yourself. When you die your 1/2 key is passed to the kids who can now open the data. The keys themselves are useless without the other keys so anyone in the chain of custody of the key until it reaches your kids wouldn't be able to open the data. No one would have to have your singular key.