As far as how high they can jump it seems to me thats not size related .In fact the lighter the MC is the easier it is for him/her to jump.
Truth is though........Some are just better at jumping than others
This is silver at 20 weeks
http://i203.photobucket.com/albums/a...cats/102-1.jpg
Silver is very long but also heavy (9lbs ) so he cant jump up as far as nero who is smaller .
At 19 weeks Nero could jump onto the worktops
My older MC floyd however is something of a jumper specialist. He was on the worktops at 13-14 weeks . He weighs 8kg ish but can get up almost anything including doors
Its not a good picture but he is sitting on a four inch ledge and the only way is straight up !
http://i203.photobucket.com/albums/a...IMG_0602-1.jpg