Unknown is related to Adventure. Adventure is related to Excitement. Excitement is a synonym of Heat. 
Building is related to Wood. Wood is related to Bird. Bird can Pet. Pet is related to Household. 
Unknown <--RelatedTo--> Adventure <--RelatedTo--> Excitement <--Synonym--> Heat 
Building <--RelatedTo--> Wood <--RelatedTo--> Bird --CapableOf--> Pet <--RelatedTo--> Household 