Melanie Klein was a psychoanalyst born in Vienna in 1892 who specialized in working with young children and developed Object Relations Theory. She believed that personality is largely a product of early mother-child relationships and emphasized interpersonal relationships, especially within the family. Her theory placed less emphasis on biologically-based drives and more on consistent patterns of relationships. Some key concepts in her theory included phantasies, objects, positions, and the paranoid-schizoid and depressive positions in child development. While her theory highlighted the importance of early development and she directly treated children, a weakness was the lack of controlled studies to validate her theories which were based on clinical experience.