For sugar mummies (huge age difference), no idea how that works.... And how the old mamas are turned on by young "boys" (with all due respect) enough to be their sons, i have no idea.....
However, I know several couples where the wife is older than husband. Like 2-4years older. I would think mostly it is the maturity, independence (as in sio kila saa "uko wapi?, unado? na nani?", not the one every man quivers when it is mentioned... like she can handle her affairs without being too dependent to a point of being suffocating..... hope you get my drift.. I think, but i could be wrong, very wrong.