In which system table does Postgres store FK cardinality?

I'm trying to reverse engineer a set of PG databases into a Data Model. I've found everything I need to define all the sub-models, tables, columns and FK constraints, but can't find anywhere that details whether the relation is 0:1, 1:many, 1:0..1 etc I've looked in

pg_constraint
information_schema.check_constraint_routine_usage
information_schema.check_constraints
information_schema.constraint_column_usage
information_schema.constraint_table_usage
information_schema.domain_constraints
information_schema.referential_constraints
information_schema.table_constraints
information_schame.key_column_usage

but there's nothing (obvious) which details the cardinality. Does anyone know where this can be found?