IMO to curtsey is very much a matter of choice.
In my country, Brasil, especially in the northern part, children would kiss their parents, and grandparents hands and ask for their blessing. It´s a custom that is still maintained in some places.
When I met members of the Brazilian Imperial family, I didn´t find at all difficult or strange to curtsey to them. Since, from childhood and being a Catholic, I had been used to show respect not only to my family´s elders, but also to bishops, archbishops, so when in front of Dom Luis de Orleans, it was the most natural thing to do.