I have just never learned to do it properly. I passed my test in 1987 (when it wasn't part of the test) and finally became a car owner in 2003. That ought to shock Oxfordshire's motorists <g> but at least I have driven a car a few times in the last few years - admittedly all in the USA [er, so which side of the car do I get in, again?] for a total of about 3300 miles - and I did take the precaution of 4 hours with a BSM instructor in 1999 before being let loose on the roads of Indiana and Ohio. Of those 4 hours, about 5 minutes were spent on parallel parking, and I didn't really reach the kerb properly even with the instructor present.
This is why J fell asleep before I got back from Tesco last night... it probably happened while I was shuffling to and fro between two cars on the street outside our house!