I'm 18 (19 no New Years Eve!) I have gone as far as 2 years younger, not sure I'd go much further unless I really fell for them! Although I doubt I'd go younger than 16 now or ever! Or even to 16 again! The immaturity I just can't stand! Age wouldn't matter too much as long as they aren't too old!! Like in their coffin before our kid even reaches one hah.