Birth order affects dating
However, critics such as Fred Townsend, Toni Falbo, and Judith Rich Harris, argue against Sulloway's theories.
A full issue of Politics and the Life Sciences, dated September, 2000 but not published until 2004 due to legal threats from Sulloway, contains carefully and rigorously researched criticisms of Sulloway's theories and data.
Results are weak at best, when individuals from different families are compared.
The reason is that genetic effects are stronger than birth order effects.
Subsequent large independent multi-cohort studies have revealed approximately zero-effect of birth order on personality.
In their book Sibling Relationships: Their Nature and Significance across the Lifespan, Michael E.
Ernst and Angst reviewed all of the research published between 19.
They also did their own study on a representative sample of 6,315 young men from Switzerland.
Among the general public, it is widely believed that personality is strongly influenced by birth order, but many psychologists dispute this.
There was, however, some tendency for people to perceive birth order effects when they were aware of the birth order of an individual.
Smaller studies have partially supported Sulloway's claims.
Consequently, there are a large number of published studies on birth order that are confounded.
Literature reviews that have examined many studies and attempted to control for confounding variables tend to find minimal effects for birth order.
Lamb and Brian Sutton-Smith argue that as individuals continually adjust to competing demands of socialization agents and biological tendencies, any effects of birth order may be eliminated, reinforced, or altered by later experiences.