Family studies of depression have yielded an average of a two to four times greater risk of depression in relatives of probands with depression than in controls. 68 Several of the earlier family studies of depression that tested sex‐specific effects did not find evidence for a sex of proband effect in either adults, 69 , 70 , 71 or youth, with equal rates of depression in relatives of male and female probands. 72 A later summary of controlled family studies of depression did not find consistent evidence for sex differences in the transmission of depression in families. 68 Likewise, family studies of bipolar disorder have not yielded evidence for sex differences in the familial transmission of this condition. 73 Most of the more recent large scale family studies based on registry data tend to adjust for sex rather than systematically investigating its role in disease transmission. 74 , 75 , 76
