It's been a while since I looked at this, but as I recall Rickman, The Corn Supply of Ancient Rome assumes that it is male heads of household since the size of the dole is rather larger than the nutritional requirements of a single adult. I may be remembering that wrong though.
Obviously that thinking has some assumptions loaded into it and at the very least would raise questions about women sui iuris (e.g. widows); I don't recall if Rickman addresses the point and I don't have it to hand.
