But when we go outside the racial field this tendency to homogamy disappears at once.  A man marries a woman who, with slight, but agreeable, variations, belongs to a like stock to himself.  The abhorrence of incest indicates that even the sexual attraction to people of the same stock has its limits, for it is not strong enough to overcome the sexual indifference between persons of near kin.  The desire for novelty shown in this sexual indifference to near kin and to those who have been housemates from childhood, together with the notable sexual attractiveness often possessed by a strange youth or maiden who arrives in a small town or village, indicates that slight differences in stock, if not, indeed, a positive advantage from this point of view, are certainly not a disadvantage.  When we leave the consideration of racial differences to consider sexual differences, not only do we no longer find any charm of parity, but we find that there is an actual charm of disparity.  At this point it is necessary to remember all that has been brought forward in earlier pages[191] concerning the emphasis of the secondary sexual characters in the ideal of beauty.  All those qualities which the woman desires to see emphasized in the man are the precise opposite of the qualities which the man desires to see emphasized in the woman.  The man must be strong, vigorous, energetic, hairy, even rough, to stir the primitive instincts of the woman’s nature; the woman who satisfies this man must be smooth, rounded, and gentle.  It would be hopeless to seek for any homogamy between the manly man and the virile woman, between the feminine woman and the effeminate man.  It is not impossible that this tendency to seek disparity in sexual characters may exert some disturbing influences on the tendency to seek parity in anthropological racial characters, for the sexual difference to some extent makes itself felt in racial characters.  A somewhat greater darkness of women is a secondary (or, more precisely, tertiary) sexual character, and on this account alone, it is possible, somewhat attractive to men[192].  A difference in size and stature is a very marked secondary sexual character.  In the considerable body of data concerning the stature of married couples reproduced by Pearson from Galton’s tables, although the tall on the average tend to marry the tall, and the short the short, it is yet noteworthy that, while the men of 5 ft. 4 ins. have more wives at 5 ft. 2 ins. than at any other height, men of 6 ft. show, in an exactly similar manner, more wives at 5 ft. 2 ins. than at any other height, although for many intermediate heights the most numerous groups of wives are taller[193].