ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Biology Open, helping researchers promote themselves alongside their papers. Heta Mattila is first author on ‘ Flavonols do not affect aphid load in green or senescing birch leaves but coincide with a decrease in Photosystem II functionality’, published in BiO. Heta conducted the research described in this article while a postdoctoral fellow in Esa Tyystjärvi's lab at University of Turku, Turun Yliopisto, Finland. She is now a postdoctoral fellow in the lab of Sónia Cruz at University of Aveiro, Portugal, investigating the effects of high light stress on different photosynthetic organisms.