For the banana-apricot-nectarine jam, peel and pit the nectarines. Peel the bananas. Peel and core the apricots.
Dice fruit, sprinkle with lemon juice and finely puree everything together. Stir in sugar and add cinnamon.
Bring everything to a boil, stirring constantly, and continue to boil for a few minutes, stirring constantly.
Rinse jam jars hot, pour in banana-apricot-nectarine jam, close tightly and store upside down.