The age distribution, , in Massonnens is; 54 children or 13.4% of the population are between 0 and 9 years old and 85 teenagers or 21.1% are between 10 and 19. Of the adult population, 34 people or 8.4% of the population are between 20 and 29 years old. 65 people or 16.1% are between 30 and 39, 68 people or 16.9% are between 40 and 49, and 35 people or 8.7% are between 50 and 59. The senior population distribution is 28 people or 6.9% of the population are between 60 and 69 years old, 20 people or 5.0% are between 70 and 79, there are 14 people or 3.5% who are between 80 and 89.