I’ve lived in Australia and France and I’ve always attributed the taller size of Australians to the excellent state of their ventilation in buildings. Vents (and rooms themselves) are systematically bigger than in France, and if you live in a healthy environment, with meat, lots out outdoors during teen age, and correctly ventilated classrooms during their 20 best years, it makes no secret to me that they grew bigger.

Meanwhile in France we heat classrooms by stacking 35 kids in a confined space. It saves on heating, plus condensation that makes windows opaque helps pupils concentrate on the blackboard, as teachers said during my childhood.