UNISEXUAL TENDENCY 15 



In the case of families of 7 or more, a unisexual tendency would be 

 shown by a deficiency in tin- numbers of families with a nearly equal 

 number of males and females. These are given in the last line of each 

 series of families. We find such a deficiency to be actually shown. The 

 numbers are : 



Actual: 101, 35, 46, 19, 25, 4, 7, 2 



Probable: 107, 39, 51, 23, 23, 7, 5, 1 



Actual sum =: 239 



Probable sum 256 



Deficit 17 



This deviation is not large enough to base a conclusion upon. It is 

 partly due to a deficit in the reports of female children in the genealogies, 

 the respective recorded numbers of male and female being: 



Number of male children 3,339 



Number of female children 3,020 



Excess of male children 319 



It thus appears that about 110 males are reported against 100 females; 

 in other words, 52.5 per cent of the whole number are males. This 

 excess over the normal is to be attributed to the greater difficulty of trac- 



J 



ing female than male children, owing to the greater liability of the former 

 to be omitted from a record, especially when they die young. 



We shall therefore expect to see a slight unisexual indication in the 

 numbers from this cause alone, so that we may regard the deviation as 

 explained without supposing any actual tendency of the kind sought. 



The general result of the count of 2838 families embracing 13,257 

 children is that the distribution of male and female offspring follows the 

 statistical laws of chance within the limits of probable deviation, the 

 actual deviations being as great in one direction as in the opposite one. 

 Consequently, there are no unisexual tendencies on the part of parents 

 sufficiently great to be of practical importance. We are not, however, 

 justified in concluding from these numbers alone that there can be abso- 

 lutely no unisexual differences in the human race, nor that no possible 

 conditions are productive of such a difference. Our conclusions only 

 preclude conditions affecting the sex of a child which may occur with a 

 certain frequency. For example, if one-tenth of the parents in the whole 

 list practiced any habit, or possessed any characteristic, which would 

 lead to two-thirds of their children being of one sex, the effect would 

 show in the statistics. But if only a single pair of parents in the whole 



