Scripture tells us little or nothing at all about the early years of Jesus. We know they had to flee to Egypt when God warned Joseph about Herod’s order to kill all males 2 years old or younger. We know they returned to Nazareth and what happened when Jesus was left behind in Jerusalem. Yet there is something important that is passed over in our hurry to get to Jesus’ ministry. The Holy Family-Mary, Joseph and Jesus-are important symbols about the family. You have two loving parents devoted to raising their son and obeying God by raising him in their faith. Their love and respect for one another, God, and Jesus are important components of what God wants the family to be. Towards the end of the 19^thcentury, Pope Leo XII (as did other popes) became concerned that the concept of the family was being diluted and in danger. So, he introduced the Feast of the Holy Family to venerate them as a model for Christian families in 1893 and set it originally on the Sunday after the Epiphany. This was changed in 1969 when it was moved to the first Sunday after Christmas to make it part of the Christmas season.

However in 2021, since Christmas Day falls on a Saturday, it will be celebrated on Sunday, 26 December. Normally this would be the Feast of St. Stephen, the first martyr, but it has been bumped off the liturgical calendar for Catholics and other Christian denominations. In countries where it is a public holiday, it will be celebrated on Monday. Boxing Day in the UK (and other countries that observe it) will take place according to the local calendar (the UK celebrates it as a bank holiday on 28 Dec 21).

Sources:
Britannica.com
Catholic Culture
Churchyear.net
Teaching Catholic Kids