Math guy here. The acceptable age difference between two persons, is governed by the following formula.
Minimum age for younger partner = Age of older partner / 2 + 7.
I didn't come up with this myself. It's floated around math departments for a while. Works well for ages above 14. Here's a sampling of the youngest acceptable partner at a variety of ages.
Current age -> Youngest person you can date
14 -> 14
16 -> 15
18 -> 16
21 -> 17/18, depending on how you round.
40 -> 27
64 -> 39
Some people might be thinking the 40/27 and 64/39 figures are off, but think about the older wealthy guys who have attractive younger wives. Their relationships are socially accepted (though maybe somewhat frowned upon), so the formula still holds true.
An interesting side note is that this formula predicts your dating pool should actually increase as you approach mid-life, as your acceptable dating range increases. See below for a graph of census data plotting age against the number of people that you can acceptably date, using the age/2 +7 rule.
(Image source:
http://www.flickr.com/photos/99956736@N00/1354376599/)
- Topher