The basis for their relationship is laid in the children's early years.
Kids who frequently visit grandma and grandpa will get to know them closely but that relationship must be worked on, especially in the years when the child undergoes big changes.
"From the age of about nine or 10 years a child goes through a process of cutting the umbilical cord and begins to orientate themselves more to the outside," says Roswitha Sommer-Himmel, a professor of education in Nuremberg, Germany. It's during this phase that their peers begin to take on greater importance.
That also means there is less time and space for grandparents.
"The child's development, naturally, has priority. A grandparent cannot insist on their vested rights such as getting a visit every summer during school holidays," warns Udo Hartings, a child guidance officer. Instead, a grandparent must seek out new ways to maintain contact.
One way is to simply arrange to meet up with them. "After all, grandparents are much fitter and more active than 20 years ago," says Michaela Obermaier, the head of the Catholic Training Institute in Germany. That requires planning and should take into account the child's changing life rhythm.
The more attractive an appointment is for both sides the more enthusiastic everyone will be. It's a good idea to link a meet-up with an event or experience.
"Going to grandma's and grandpa's was usually connected with a certain ritual for a child such as a game or a favourite food. Rituals like that should be maintained," says Obermaier.
But there should also be room for new things like shared hobbies. "Because grandparents are much fitter these days it's a good idea to get involved in outdoor activities," suggests Hartings.
That does not mean granddad has to get over-enthusiastically involved with football just because his grandson likes it. "But he should be prepared to go to a match," says Sommer-Himmel.
The more grandparents know about their grandchild the easier it is to understand their interests and needs.
By talking to the parents and keeping an eye on the media, grandparents can keep up to date with the latest trends and topics affecting their grandchild.
"They can also ask their grandchild to bring along their favourite book or music CD," says Sommer-Himmel.
In cases where grandparents are seeing less and less of their grandchild they can fall back on other forms of communication to keep the relationship going.
"New technologies offer amazing opportunities to keep the connection warm," says Hartings.
Kids are usually much more familiar with mobile phones, computers and other electronic devices than older generations.
"Grandparents often end up getting introduced to new technologies by their grandchildren. That can also turn into a very enjoyable experience for both sides."
How involved are your children's grandparents?