This is an interesting study of the figure of Seth/Set in various texts and traditions. The Egyptian Seth-Horus narrative is fleshed out in a separate article by the same author.
The marriage between the lines of Cain and Seth (endogamy) is not developed. Analysis of the marrriage and ascendancy pattern of these early rulers is based on the data provided in the Genesis 4 and 5 king lists. the kinship analysis reveals that the descendants of Cain and Seth intermarried and that the cousin brides named their first-born sons after their fathers.