I don't see what difference it makes as far as sex goes. I like 'em bigger, myself, but I find all sorts attractive. I don't usually find flat chests attractive, but there is always other attributes a woman may have that compensates for that, such as a cute butt, or a nice little cameltoe pussy, or big dreamy eyes, or a pretty mouth...the list goes on. Really, the only thing that is affected is titty-fucking, which is something I've always liked, but there's a million ways to get off with a woman, so it doesn't matter that much, overall.