I never disagreed with you about sperm! In my original comment I asserted that men weren't really marriagable material until around age 25. The age difference that seems ideal here isn't all that great, and there's still a lot of room for men and women of the same age to marry at both their ideal ages when they're at the same age in the classical college tradition of meeting your sweetheart in college, perhaps marrying a year after college, and then waiting a bit more to start having children. What age difference do you think would be too much?