Would Mary and Joseph's parents have gone to Bethlehem also?

At the time of Luke's journey from Nazareth to Bethlehem, Mary and Joseph were only bethrothed, and Mary was still a virgin. We can assume that they were both in their teens, with Mary probably in her early teens. Their parents would likely still have been alive and less than forty years old. If there really was a census during the reign of King Herod, something most scholars dipute strongly, then Joseph's parents would have been expected to go Bethlehem as well. Tradition tends to support the notion that Mary was also descended from King David, although The Bible is silent on this, in which case we could also expect her parents to travel to Bethlehem as well. However, for some reason, Luke's Gospel makes no mention of the extended family travelling together to Bethlehem.