My dad died in 1978. His sister died in 1983.
My mom is married to my dad's sister's husband.(my uncle)
So my "sister" is really my "cousin."
ANYWAY, my mom is so concerned that everything is equitable. She'd do that for my brother and I growing up, counting the presents, etc. I don't think we ever really paid any attention to it.
But now, if my "sister's" son gets my son something, we have to return equal or greater value (in her eyes).
But we resist. We've managed to make an art form out of finding quirky, inexpensive gifts. And they're always a hit.