Database for inheritance hierarchy queries

I'm looking for a way to store hierarchical data, in a way that will facilitate "inheritance" queries that will coalesce upwards in the hierarchy. Simple example:

Level 1, property X = 123
 - Level 2, property x  = null
 - - Level 3, property x = null

What is the effective value of property x at level 3? Answer: 123 (because it coalesces up to level 1). Is there a database engine that is purposely made for this type of structure? This can be done relationally, or possibly in a graph, with some effort, but I am trying to find an engine natively optimized for this.