原始表达：

"Due to the fact that our grandparents were under an obligation to help their parents..."

优化建议：

"Because our grandparents were obligated to help their parents..."

复杂句式转换：

原句："The situation that resulted in my grandfather's not being able to study engineering was that his father needed help on the farm."

优化版本：

"My grandfather couldn't study engineering because his father needed help on the farm."