To put it crudely: the harshness of colonial life required a large, healthy, (and somewhat expendable) workforce. The institution of marriage, and the emphasis on large families, was the vehicle by which this was achieved. For obvious biological reasons, opposite gender pairings were a necessary component of this way of life. Historic Christianity has also played a significant role in the emphasis of the traditional “one man and one woman” marriage paradigm. Notably, the Roman Catholic and Orthodox churches have also stood against two of the more potent forces eroding the sanctity of marriage (i.e. contraception and more lax divorce requirements).
To put it crudely: the harshness of colonial life required a large, healthy, (and somewhat expendable) workforce. The institution of marriage, and the emphasis on large families, was the vehicle by which this was achieved. For obvious biological reasons, opposite gender pairings were a necessary component of this way of life. Historic Christianity has also played a significant role in the emphasis of the traditional “one man and one woman” marriage paradigm. Notably, the Roman Catholic and Orthodox churches have also stood against two of the more potent forces eroding the sanctity of marriage (i.e. contraception and more lax divorce requirements).