Experimental Design. Experimental design is shown for two of the 27 full sib families (see Methods for full explanation). Each family started with > 60 recently hatched larvae split into two blocks (A and B) of 30 larvae that produced roughly equal numbers (< 15) of brothers (bros) and sisters. For each of the 54 combinations of full sib family*block, four sisters were randomly selected for wing length (WL) measurements and the remaining females were split between two cages (I and II) where the females (now dams) received their first blood meal (Blood 1). For each of the 27 sire families in block A, ten brothers were randomly selected and combined with five randomly selected blood-fed dams from cage I. These mixed-sex swarms were allowed to mate for 24 hours, after which the males were removed and the dams were given their second blood meal. Two days later this process was repeated for the 27 sire families in block B and the blood-fed dams from cage II. For each of the 54 mating cages, the wing length of four randomly selected brothers and all 5 dams were measured. Blocks A and B are shown with solid and stippled lines, whereas brothers, sisters and dams are colour-coded black, green and red.