1. BACKGROUND In the last ten years there has been much popular discus sion and also a great scholarly interest in the so-called "alternative lifestyles" (1). ESgecially, since the late 1J60's, a diversity of lifestyles other than the nuclear family began to emerge, according to demographic changes in household compositions during the past decade (US Bureau of Census, 1979; Centraal Bureau voor de Statistiek, 1930). One lifestyle, non-marital cohabitation, has increased most dra matically durin ...