This article points out: “The combination of men and women in families is irrational.” Men and women are two different “species.” They only require sexual activities from each other, which are considered the less time-consuming activities during their lives. Sex must be treated as an enemy of marriage, due to its inferior and treacherous nature, and should not be included in marriage. Men and women should not live together in a family, since this institution must be understood as a permanent (...) place for all family members and is expected to have a solid structure. The traditional family model is the result of men‟s enslavement of women and the exaggeration of the role of sex. This model creates an overwhelming advantage for men in selecting partners, proposing marriage, and other family activities. This article indicates: (i) The prominent family models existing between the group-marriage period and now are sex-based family models. (ii) Technical and social conditions nowadays require a new and sustainable base for a family. The selected targets in this study are the consanguineous and sworn relationships among same-sex people in case they choose to be heterosexual, (and in turn, among opposite-sex persons when they engage in homosexuality). For example, a family can consist of two blood brothers (or sworn brothers or cousins) with their children, in case they are heterosexual. This family model is named the non-sex based family (NSBF) model, since the sexual needs will be met outside the family. The article also outlines a post-patriarchal society with the presence of NSBFs, and argues that the new model should be seen as an essential development trend of society. (shrink)