I have two Jade plants on both the leaves have started becoming yellow/red

on one of the plants the leaves are no longer stiff and strong, but a little wrinkly and and feel soft. this is on most leaves

on the other plant again some yellow and red leaves, but i new leaves growing are an odd shape - they look like the clubs picture in a packet of cards.

both plants are next to each other on my window sill. they get a lot of light, but not directly as i have a net curtain between the window and the plants.

I rarely water it..but i cant be sure if anyone else in my house hold has been watering it.

any advice?