Food neophobia refers to reluctance to eat unfamiliar foods. We determined the heritability of food neophobia in a family and a twin sample. The family sample consisted of 28 Finnish families (105 females, 50 males, aged 18-78 years, mean age 49 years) and the twin sample of 468 British female twin pairs (211 monozygous and 257 dizygous pairs, aged 17-82 years, mean age 55 years). Food neophobia was measured using the ten-item Food Neophobia Scale (FNS) questionnaire, and its internationally validated six-item modification. The heritability estimate for food neophobia was 69 and 66% in Finnish families (h(2)) and 67 and 66% in British female twins (a(2)+d(2)) using the ten- and six-item versions of the FNS, respectively. The results from both populations suggest that about two thirds of variation in food neophobia is genetically determined.