That's very interesting!
I am the eldest too, but I didn't have the same kind of things to do for the younger kids because my mom was always around. I did have to look after them a lot of weekend nights when my parents went out to socialize with friends or neighbors, and left me in charge of the kids. I just had to make sure they went to bed on time, and then stay awake and make sure everything was okay. I watched a lot of late night TV on those days!
Is your mom a full time housewife? Lucky for you that she is around. Both my parents are working back then, and my mom sometimes even have to work out of town for a week. It was a huge responsibility back then, especially when both of them are not around till night time.
Yes, she did not work in those days. Even when the youngest went to school and she did go back to work, it was just part time so she would be home when they got home from school. That was typical for the area we lived in, and we took it for granted that mom would be home with the kids, but its not that way for everyone. Looking back, I'm grateful for it, although I can see your point about learning responsibility when you have to take care of others!