Cute Young Brunette Girl With A Fringe Undresses Her White Knickers On The Bed With A Little Red Rose And Petals Leaves

Genetics
The genetics behind the formation of petals, in accordance with the ABC model of flower development, are that sepals, petals, stamens, and carpels are modified versions of each other. It appears that the mechanisms to form petals evolved very few times (perhaps only once), rather than evolving independently from stamens in a large number of plants.