Endogamy is the practice of marrying or associating with members of your own clan or social group. Exogamy is that of marrying or associating with those of exterior clans, groups, races etc. We are more exogamous than we used to be, but perhaps not as much as we think. When I try and situate myself within this spectrum it is difficult to know whether the partners or close friends I have associated with in the past have attracted you to them by some elements that recall myself and my own clan, even though they may have elements that are clearly alien (race, colour, social class). Equally, life pulls you away from your home clan. You may go away to study and never return. Over the years the notion of home gradually disolves. Moreover, your home clan may in itself be a complex uncentred atom, more electron than neucleus. It might also be that you find extraneous elements in the other that refer you to yourself but may be peripheral to other viewers, elements to do with those modern things like common tastes and outlooks. Or, and this may well be the case for me, it may be that it was never you making the choice in the first place, but the other.