Purpose The purpose of this paper is to examine the influence of ability, desire and opportunity on the individual's intention to be self-employed. Design/methodology/approach The authors created a database from Swedish national registers consisting of all individuals residing in Sweden sometime during the period 1997-2010 and selected all 333,001 full sibling pairs, 12,810 maternal half sibling pairs and 15,944 paternal half sibling pairs. Three types of entrepreneurs were defined based on information from the Swedish Tax Register. The authors divided the intention to be self-employed into ability and desire and defined ability as a genetic factor and desire as a common family factor. A classical twin model was used to separate the variance of the outcome variables into genetic, common and unshared environmental factors. Findings The study demonstrates that the influence from opportunity on the intention to be self-employed is generally strong and that all factors, ability, desire and opportunity, differ, both in size and content, for the three outcomes of entrepreneurs. Originality/value The authors divide self-employment into three distinct company types, which enables a sophisticated additive genetic analysis of the ability, desire and opportunity to be self-employed. The authors contribute to the understanding of why individuals become self-employed by examining the influences from internal and external factors of family on the intentions of self-employment.