We examine demographic behaviour of Jewish adults of mixed ethnic ancestry, relative to those of the two major Jewish ethnic groups in Israel. Research has shown that for measures of socioeconomic status, such as educational attainment, outcomes for multi-ethnics are in between - and very close to the middle of - those associated with the two major ethnic groups. We find that, in contrast, the marriage and fertility behaviour of multi-ethnic adults is nearly identical to that of the more socially advantaged ethnic group and quite distinct from that of the less advantaged ethnic group. Through multivariate analyses, we explore factors associated with families of origin, including socioeconomic status and cultural indicators of family norms, which are associated with these patterns. We discuss interpretations of our findings.