A 40-year-old man yesterday stabbed his 26-year-old wife to death in their home in the southern Athens district of Kallithea before grabbing his two sons, aged 2 and 3 years old, and jumping off the balcony of his fifth-floor apartment, killing himself and his youngest son, police said. The 3-year-old boy was in the intensive-care unit of an Athens hospital yesterday after sustaining serious injuries in the fall, which occurred at around 3.30 p.m. The man and his sons had landed on the roof of an adjacent three-story building. The 40-year-old had earlier used a kitchen knife to repeatedly stab his wife in the throat, according to police, who said they found a note in the apartment explaining the reasons for the attack. No details were provided about the content of the note.