How old is it normal for kids to wipe themselves?

No.

By about 4 years old you expect them to be independently using the toilet. It doesn't necessarily mean that they will be doing a good job at wiping, but they should be wiping nonetheless.

Ha! I just had this conversation with my husband. Usually between 3-4 they can sort of do it. It is required by most preschools to be potty trained. However they do an awful job at it. Usually by 7-8 they start to understand how to wipe themselves clean. So while my 4 year old still asks for help, his butt and underpants are much cleaner than my 6 year olds.

The 7 year old who asks may have some developmental issues or extreme helicopter parents. Or, maybe the kid was having bowel trouble.

My cousin's son is autistic and cant wipe his own ass at the age of 10. I dont think he's incapable of it, both his parents are just useless lazy cunts

That's nasty. Then again some kids suckle on there moms for years and years. Some family's are just weird. Like the ones who kiss there kids on the lips like what the flipping heck. Nasty. Then again target sells a dress for little girls and it very short cut. The kind you were when you want dick at a club. It's on a freaking mannequin! I don't understand this world anymore