The age distribution, , in Onsernone is; 14 children or 4.7% of the population are between 0 and 9 years old and 23 teenagers or 7.8% are between 10 and 19. Of the adult population, 30 people or 10.2% of the population are between 20 and 29 years old. 19 people or 6.4% are between 30 and 39, 34 people or 11.5% are between 40 and 49, and 61 people or 20.7% are between 50 and 59. The senior population distribution is 48 people or 16.3% of the population are between 60 and 69 years old, 34 people or 11.5% are between 70 and 79, there are 32 people or 10.8% who are over 80.