According to Karel van Mander, who mentioned him in his biography of his father Pieter Aertsen, he followed in his father's footsteps but took to portrait painting because large commissions were not to be had.
[1] Van Mander did mention a large painting for the Baker's guild of Haarlem, which is in the possession of the Frans Hals Museum today, and which Van Mander described as very fiery and original.
[1] According to the Rijksmuseum, he married Magdalena Pietersz, the daughter of a glass painter in Haarlem in 1574.
[3] According to the RKD he was called "Jonge Lange Pier" as the oldest son of the painter Pieter Aertsen ("Lange Pier").
He received many commissions and was a wealthy man at the time of his death in Amsterdam.