An haifi Meester a Fort Worth, Texas, zuwa Constance Lynn (née Haas) da Douglas Jay Meester. Mahaifinta ya kasance mai ba da izini ga masu aikata laifuka, kuma mahaifiyarta marubuciya ce. Tana da 'yan'uwa biyu; wani ɗan'uwa, Douglas Logan Meester (an haifi 1983), da kuma ɗan'uwa, Alexander "Lex" Meester (an haifi 1994). A lokacin haihuwarta, iyayen Meester suna yin zaman kurkuku a kurkuku na tarayya saboda haɗuwarsu da wani ƙwayoyi da ke safarar marijuana daga Jamaica zuwa Amurka. Constance ya iya haifa Leighton a asibiti da kuma jinya ta tsawon watanni uku a cikin gidan rabin hanya, kafin ya koma kurkuku don kammala hukuncinsa. Iyayenta na mahaifinsa sun kula da Meester a wannan lokacin. Ta ci gaba da cewa iyayenta sun ba da laifi, duk da watanni da suka gabata, kuma mahaifiyarta ta kasance mai kirki, ta fahimci cewa Bruce Meester (an haife shi a 1983), da kuma dan uwansa, Alexander "Lex" Meester (an haife shi a 1994).
watanni uku