If this trisomic fly is the progeny of a male fly of genotype (ey+ ey−, gw+ gw−) crossed to a female fly with genotype (ey− ey−, gw− gw−), what can you conclude about the events that led to its formation? if this trisomic fly is the progeny of a male fly of genotype ( , ) crossed to a female fly with genotype ( , ), what can you conclude about the events that led to its formation? nondisjunction occurred in the male parent at the meiosis ii division to produce an (n+1) sperm that fused with a normal (n) egg. nondisjunction occurred in the male parent at the meiosis i division to produce an (n+1) sperm that fused with a normal (n) egg. nondisjunction occurred in the female parent at the meiosis ii division to produce an (n+1) egg that fused with a normal (n) sperm. nondisjunction occurred in the female parent at the meiosis i division to produce an (n+1) egg that fused with a normal (n) sperm.