I don't care how they sing. Jackson advises developing family rituals that don't cost anything. They don't necessarily need to take up a lot of time either, but the defining quality is they happen every year. Playing the same music. Reading the same story aloud.
Families looking for a religious dimension to their holiday can read from the Bible.
They like it that dad and mom repeat it every year. It adds stability to the experience. The family meal can embody the same ritual quality. On the holidays you can get together around food and try to converse around the table. Stress may be endemic to the holiday season, but it generally doesn't lead to full-blown mental health crises.