Honestly...i don't think a child is ever too young to at least get the basic of chores and haousehold tasks.
I know from personal experience that this is true. My mom has a chronic seizure disorder. She had brain surgery to "cure" it many years back, and is fine now...but as a child I had to be the grownup.
My dad worked 2 jobs to take care of medical bills and etc, and that left me and my brother to take over at the house. My mom would have major grand mal seizures several times a week... most of the time they were controllable, but often sadly they were not, and we would have to call 911.
So, when I was 6 years old, my grandmother came to live with us for a while to help with my little 2 year old brother and myself when my mother was put into hospital again. I learned how to cook, clean, take care of the animals we had, make beds, vacuum and so on. She and my grandad stayed around to help out as they could, but they both passed on before I was 10. I basically took over the house at that time.
Made sure myself, my mom, my brother and dad had clean clothes to wear....made sure we had lunches made, dinner cooked, homework done, and so on. My mom would try to help as she could, but many times she was unable to do so due to being in hospital or sleeping off a seizure.
I did the entire Thanksgiving dinner for our family <the four of us> at age 10!!! My dad helped me get the turkey in and out of the the oven, but pretty much it was all me
My mom tried so hard...but she just couldn't do it. She seized out in the kitchen before we even got truly started.
So yes...kids can learn at a young age and I think its a great thing to learn!! I ended up working with kids for a long time, and it always shocked me at how little they were expected to do. The way I see it is if you are old enough to have the physical skills, you should be helping out. Little ones can help make sandwiches and fold clothes and help dust... bigger ones can help dry dishes and separate clothes AND start the wash as well. Older ones can do more...vacuuming, making dinner and so on. No reason for kids to not know basic skills imho. Make it fun, make it a game, let them know they are helping...and it is a charm.
And, in case anyone is curious, the surgery was a limited success.... my mom has not had a seizure since the surgery back in 1992. However, she has tunnel vision, bad balance, and bits of memory loss, mostly of her years before the surgery. She also has short term memory issues... she often forgets things, and her personality is much MUCH different than before. She isn't the same person I grew up with....but still my mom. For instance, my mother growing up would NEVER allow us to swear or anything remotely close to it. Now she has a mouth like a sailor... I am always surprised what comes out of there at times...its like the "off" switch is broken. And she doesn't seem to have the ability to think before she speaks....it's always an adventure when we go somewhere in public...we never know what she will say. It's really like being with a kid...they don't mean to be rude or hurtful ...it just comes out that way.
Not really sure if the gains were worth the losses tho, but its been almost 20 years now, and we have learned to live with it. I still make the dinners tho when I am home...she forgot how to cook and my dad tries lol
I was mostly raised by my grandma (mom worked nights), but she did most of the cleaning when I was at school or outside playing. I only had to make my bed and help dry the dishes. I had a crash course in laundry before I went away to college. Now, I hate doing dishes, hate housework, hate laundry. I'm a SAHM and no one else is going to do it... 
