"Ewan Birney, co-director of the European Bioinformatics Institute near Cambridge added: “This is an interesting study where using genetics one can better untangle cause and consequence of a complex human behaviour. Genetics only contributes a small part to age of first sexual intercourse, but the very random nature of each person’s genome means it can be used to trace the impact of this behaviour into later life with less concern about complex correlations confusing cause and consequence."