Birth order refers to a child's position by age in relationship with their sibling(s): oldest, middle, youngest. Many people, both psychologists and the general public, believe that a child's position in the family has profound and lasting effects on their personality. However, scientists have mixed opinions about the significance of birth order. Alfred Adler, a contemporary of Freud and Jung, believed that a person's place in the birth order made for profound influences in an adult's lifestyle, ways of dealing with tasks, and the mindsets that go with friendship, love, and work. More recently, theorists have put forward the theory of the "Big 5" personality traits (Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism) and studying how birth order interacts with these traits. Additional research tends to relate personality development to family size more than birth order in the presumption that large families are more often less affluent and that this lack of material advantage has a greater influence on the individual than birth order.