Exploration of the strength of family links

Ever since the studies of Louis-Adolphe Bertillon in the late 19th century it has been known that marital status and number of children markedly affect death and suicide rates. This led in 1898 Emile Durkheim to conjecture a connection between social isolation (especially at family level) and suicide. However, further progress was long hampered by the limited statistical data available from death certificates. Recently, it was shown by the present authors that disability data from census records can be used as a reliable substitute for mortality data. This opens a new route to investigations of family ties because census information goes much beyond the limited data reported on death certificates. It is shown that the disability rate of adults decreases when they have more family links. More precisely, the reduction of the parents’ disability brought about by the presence of a child reveals that the strength of ties between parents and child is highest in the first year after birth and then weakens steadily as the child ages. It will also be seen that the strength of the bond between husband and wife is highest when they are of same age and decreases fairly steadily when the age gap increases.