 She was the eldest daughter of the physicist Hendrik Lorentz and Aletta Catharina Kaiser.In 1910, she married the physicist Wander Johannes de Haas and they had two sons and two daughters.Geertruida Lorentz studied physics at the University of Leiden under her father, and earned her doctor's degree in 1912 on a thesis entitled ""Over de theorie van de Brown'schen beweging en daarmede verwante verschijnselen"" (On the theory of Brownian motion and related phenomena).