What Is It With Spaghetti?

Tonight I cooked spaghetti bolognaise, but why is it whenever I cook spaghetti I have this uncontrollable urge to add more than I need! Consequently by the time it's cooked I have enough to feed the whole of NW London (ok slight exaggeration I know!) but you know what I mean!

No matter how hard I try I always have to add more to the pot, it never ever looks like I've got enough to feed everyone and then as if by magic seems to triple, no quadruple in size and I end up throwing loads of it away :(

So if anyone has a sure fire way for cooking just the right amount of spaghetti would they please let me know!