Family aggregation, also known as familial aggregation, is the clustering of certain traits, behaviours, or disorders within a given family. Family aggregation may arise because of genetic or environmental similarities.
Schizophrenia
The data from the family aggregation studies have been extensively studied to determine the mode of inheritance of schizophrenia. Studies to date have shown that when numerous families are studied, simple modes of inheritance are not statistically supported. The majority of studies analyzing for the mode of inheritance have concluded that a multifactorial threshold mode is most likely.2
Cardiovascular problems
The most consistent and dramatic evidence of family influences on cardiovascular disease (CVD) is family aggregation of physiological factors. In several studies the parent-child and sibling-sibling correlations of blood pressure are approximately .24. Genetic determination of blood pressure is strong, but does not explain all of the variance.3
Parkinson's disease
Familial Parkinson's disease (PD) exists but is infrequent. Early investigations failed to show substantial family aggregation for PD.4
References
Butcher, J., S. Mineka, and J. Hooley. Abnormal Psychology. 15. Boston: Pearson, 2010. Print. ↩
Allan Ed. Tasman (1 May 1991). American Psychiatric Press Review of Psychiatry, Volume 10. American Psychiatric Pub. pp. 83–. ISBN 978-0-88048-436-7. Retrieved 10 January 2013. 978-0-88048-436-7 ↩
Sonya Bahar (31 August 1988). Health Behavior. Springer. pp. 108–. ISBN 978-0-306-42874-6. Retrieved 10 January 2013. 978-0-306-42874-6 ↩
Karel Vuylsteek; Manuel Hallen (1994). Epidemiology: Results of the 4th EC Medical and Health Research Program. IOS Press. pp. 194–. ISBN 978-90-5199-150-5. Retrieved 10 January 2013. 978-90-5199-150-5 ↩