My parents are not particularly religious, but they do practice ancestor veneration, which is a part of Confucianism, Taoism, and Chinese Buddhism.
One ritual I have watched my parents practice over the years has been burning incense and praying to our ancestors before any of us embark on any travel: when all of us kids are back in Virginia for Christmas, our parents burn incense before any of us depart again; my sister Lisa believes this ritual is so we receive protection from our ancestors to travel home safely.
My parents also burn incense during Chinese holidays and other important dates; during those times, they also prepare food for the ancestor altars; when we kids are actually at home, our parents ask us to follow them to the altar to bow three times to each ancestor. After we have all paid respect to our ancestors, we proceed to eat the leftover food from the ritual.
In our first house, we had a large back room where my grandmother had her sewing machine and supplies, and we had our laundry machines and our ancestor altars with incense holders. These days at our current house, we’ve converted a small closet in our study into the ancestor altar. My parents close the doors to the altar whenever we have guests visiting so to not disturb the altars to our ancestors.
I think my parents also close the door so to not draw out any curiosity from the grandchildren, to explain the meaning behind the altars. None of my niece or nephews know about the altars; they may never know the true meaning behind this tradition since none of us kids practice ancestor veneration on our own.